in 1801, in a mineral from Massachusetts; and by M. Ekeberg, in 1803, in
tantalite, a mineral found in Sweden. It exists in most of its ores in
combination with oxygen.
=TAPEWORM.= See WORMS.
=TAPEWORM CURE= (Bloch, Vienna). Coarsely powdered pomegranate root bark,
125 grammes, boiled for half an hour in 800 grammes water. To this add
solution of ammonia, 5 grammes; boil again for a quarter of an hour. Add
kousso flowers 25 grammes. Again boil for a few minutes, and when cold add
citric acid, 1 gramme; and alcohol, 30 grammes. Press, filter, and set
aside. The product should weigh about 500 grammes. Klinger says this
remedy is merely a concentrated essence of pomegranate root bark, and
contains neither ammonia nor citric acid.
=Tapeworm Cure= (Jacoby, Berlin). A box containing 20 grammes of kousso
powder and directions for use. (Hager.)
=Tapeworm Cure= (Mix). (_a_) A mixture containing 3 decigrammes of
sulphate of quinine, with a few drops of hydrochloric acid to dissolve it
in 200 grammes water. To be taken in the course of three days. (_b_) A box
with 12 grammes kousso powder. A teaspoonful to be taken each morning in
black coffee. (Schädler.)
=Tapeworm Cure= (Richard Mohrmann, Frankenberg, Saxony). This Mohrmann
travels about in the fashion of the old charlatans, to sell his medicines.
These consist of two varieties, the first being 10 grammes of extract of
male fern, the second a mixture of 8 grammes each of raspberry juice and
castor oil. These remedies have been used for tapeworm for almost 100
years. The doctor’s directions for use are to mix 30 grammes of the
extract with the castor oil and raspberry compound, and 30 drops of the
mixture to be taken every quarter of an hour, until purging occurs.
=Tapeworm Cure= (Mork, Berlin). A decoction of about 110 grammes of
pomegranate root bark, yielding 400 grammes of liquid, and mixed 1 gramme
of extract of male fern. The directions order that on one day one or two
tablespoonfuls of castor oil should be taken, a herring salad in the
evening, and the following morning, after coffee, a third of the contents
of the bottle, another third half an hour later, and the remainder in yet
another half hour. (Hager.)
=Tapeworm Cure for Children and Adults= (E. Karig, Berlin). Burned oxide
of copper, 1 gramme; cassia powder, 1-1/2 gramme; sugar of milk, 10
grammes. Divide in 24 powders. (Schädler.)
=Tapeworm Pills, Laffon’s=, are compounded of the ethereal extract of the
root of _Aspidium Lonchitis_, _Asp. Helveticum_, and _Asp. Filixmas_,
together with the alcoholic extract of the flowers of _Achillea mutellina_
and _maschata_, and the powder of the flowers of _Arnica Doronicum_.
(Wittstein.)
=Tapeworm Pills, Peschier’s.=——Ethereal extract and powder of the rhizome
of male fern, of each gramme 1·6 make 20 pills. Take ten at night and ten
in the morning.
=TAPIO′CA.= _Syn._ TAPIOCA (Ph. E. & D.), L. The fecula of the root of
_Janipha manihot_ (_Jatropha manihot_——Linn.), which has been well washed
in water, and dried on hot plates, by which it assumes the appearance of
warty-looking granules.
[Illustration: Microscopic appearance of tapioca.]
Pure tapioca is insipid, inodorous, only slightly soluble in cold water,
but entirely soluble in boiling water, forming a translucent and highly
nutritious jelly. Its granules are muller-shaped, about 1/2000 of an inch
in diameter, and display very marked hilums. It is used in a similar
manner to sago and arrow-root. See CASSAVA.
=TAPS, WOODEN (to prevent their cracking).= The taps are placed in mother
paraffin, heated to from 110° to 120°; by this means the water is
eliminated from the wood, and the wood becomes thoroughly impregnated with
paraffin. The taps are heated in this bath until all the aqueous vapour
has been expelled, and are left in it, after the removal of the vessel
from the fire, up to the very moment the paraffin begins to solidify.
Wooden taps thus prepared are very durable, do not become soaked with
liquids, keep very tight, and are not liable to become mouldy. The excess
of paraffin is wiped off with care, and the taps are next rubbed clean
with a piece of flannel. (Dr E. Kopp.)[224]
[Footnote 224: ‘Chemical News.’]
=TAR.= _Syn._ PIX LIQUIDA (B. P., Ph. L., E., & D.), L. A liquid bitumen
prepared from the wood of _Pinus sylvestris_, and other species, by heat.
The chemical constitution of tar is very complicated. Its uses in the arts
are well known. As a medicine it is stimulant, diuretic, sudorific, and
vermifuge.——_Dose_, 20 to 60 minims, made into pills with flour; in
ichthyosis, &c. Externally, in lepra, psoriasis, foul ulcers, &c. See
OINTMENT and INFUSION.
=Tar, Barbadoes.= _Syn._ PIX LIQUIDA BARBADENSIS, PETROLEUM BARBADENSE,
PETROLEUM (Ph. L. and E.), L. “Black liquid bitumen, exuding spontaneously
from the earth.” (Ph. L.) Its properties for the most part resemble those
of the last.——_Dose_, 10 to 30 drops; in asthma, chronic coughs, tapeworm,
&c. Externally, in chilblains, chronic and rheumatic pains, &c. See
PETROLEUM.
=Tar, Coal.= Produced during the distillation of bituminous coal for gas.
See NAPHTHA, &c.
=TARAX′ACUM.= See DANDELION.
=TAR COLOURS.= _Syn._ COAL TAR COLOURS, ANILINE COLOURS, &c. Coal tar, the
source of the aniline colours, consists of the oily fluid obtained in the
destructive distillation of coal, during the manufacture of ordinary
illuminating gas, and collected in a tank from the hydraulic main and
condensers.
The composition of coal tar is highly complex, the most important
constituents being, however, a series of homologous hydrocarbons obtained
by distilling coal tar, and known as ‘coal naphtha.’ Naphtha, by
rectification between 180° and 250° Fahr. (82 and 121 Cent.), yields a
light yellow oily liquid, of sp. gr. ·88, the benzol of commerce.
By the action of a mixture of nitric and sulphuric acids on benzol,
nitro-benzol, a heavy oily liquid with an odour of oil of bitter almonds
is obtained. In commerce this substance is made in large cast-iron pots,
fitted with tight covers, and provided with stirrers worked by steam
power. By means of pipes the reagents are admitted and the nitrous fumes
are carried off, while the nitro-benzol and the spent reagents are drawn
off from the bottom. The entire charge of benzol is first placed into the
vessels, and the mixed acids are, as the reaction is very energetic,
cautiously run in, the whole being well stirred throughout. When finished,
the contents are drawn off, and the nitro-benzol collected, washed with
water, and, if necessary, neutralised with a solution of soda. See BENZOL.
Nitro-benzol is converted into aniline in a similar apparatus, only
provided with means of admitting a current of superheated steam, and
condensing the aniline as it distils over. Into the vessel iron borings
are placed, and acetic acid and nitro-benzol cautiously run in as the
reduction is violent, stirring well all the time. A current of superheated
steam is passed through, and the aniline collected as it distils over as a
pale, sherry-coloured oily liquid, boiling at 360° Fahr. (182 Cent.), and
of sp. gr. 1·02. See ANILINE.
MAUVE, INDISINE, VIOLINE, PHENAMINE, the first-discovered coal tar, or
aniline colour, was obtained by Mr Perkins during some experiments
directed towards the artificial formation of quinine, and was also first
practically manufactured by Mr Perkins. Commercially, mauve is made as
follows:
Aniline and sulphuric acid in proper proportions are dissolved in water in
a vat by aid of heat, and when cold a solution of bichromate of potassium
added, and the whole allowed to stand a day or two, when a black
precipitate is obtained, which, after collecting on shallow filters, is
washed and well dried. This black resinous substance is digested with
dilute methylated spirit in a suitable apparatus, to dissolve out the
mauve, and the major portion of the spirit distilled off. The mauve is
precipitated from the aqueous solution left behind by hydrate of sodium,
and after washing is either drained to a paste or dried.
The amount of mauve thus obtained is but small in comparison with the raw
material, coal tar, as 100 lbs. of coal yield 10 lbs. 12 oz. of coal tar;
8-1/2 oz. of mineral naphtha, 2-3/4 oz. of benzol; 4-1/4 oz. of
nitro-benzol, 2-1/4 oz. of aniline, and 1/4 oz. of mauve. Mauve is usually
sent into the market in paste or solution, the expense of the crystals
being heavy, and offering no corresponding advantages.
Other salts than the bichromate of potassium have been employed to convert
aniline into mauve, as chloride of copper, permanganate of potassium, &c.;
but experience has shown none to possess the same advantages as the
bichromate of potassium.
MAUVEINE, the organic base of mauve or aniline purple, is a black
crystalline powder, of the formula C_{27}H_{24}N_{3}, yielding a dull
violet solution. The moment, however, mauveine is brought in contact with
an acid, it turns a magnificent purple colour. The salts of mauveine form
beautiful crystals possessing a splendid green metallic lustre, soluble
very readily in alcohol, and less so in water. The commercial salt, or
mauve, is the acetate, or sometimes the hydrochlorate.
=Magenta.= _Syn._ ANILINE RED, ROSEINE, FUCHSINE, AZALEINE, SOLFERINO,
TYRALINE. Various processes have been proposed and patented for the
preparation of this commercially important coal-tar colour. Amongst these
processes are——
1. Gerber-Keller’s, patented in France, October 29th, 1859. By this the
aniline is treated with mercuric nitrate.
2. Lauth and Depouilly used nitric acid.
3. Medlock (patent dated January, 1860). Nicholson, and Messrs Girard and
De Laire, all in 1860, separately patented the use of arsenic acid. This
process, being the one now almost exclusively employed, is thus described
in Crace Calvert’s work, ‘Dyeing and Calico Printing,’ edited by Messrs
Stenhouse and Grove. “The manufacture of magenta, as it is now conducted
in the large colour works, is a comparatively simple process, the
apparatus employed consisting of a large cast-iron pot set in a furnace,
provided with means of carefully regulating the heat. It is furnished with
a stirrer, which can be worked by hand or by mechanical means, the gearing
for the stirrer being fixed to the lid, so that by means of a crane the
lid may be removed, together with the stirrer and gearing. There is also a
bent tube passing through the lid for the exit of the vapours, which can
be easily connected or disconnected with a worm at pleasure; lastly, there
are large openings at the bottom of the pot, closed by suitable stoppers,
so that the charge can be removed with facility as soon as the reaction is
complete. Into this apparatus, which is capable of holding about 500
gallons, a charge of 2740 lbs. of a concentrated solution of arsenic acid,
containing 72% of the anhydrous acid, is introduced, together with 1600
lbs. of commercial aniline. The aniline selected for this purpose should
contain about 25% of the toluidine.
“After the materials have been thoroughly mixed by the stirrer the fire is
lighted, and the temperature gradually raised to about 360° F. In a short
time water begins to distil, then aniline makes its appearance along with
the water, and, lastly, aniline alone comes over, which is nearly pure,
containing, as it does, but a very small per centage of toluidine. The
operation usually lasts about eight or ten hours, during which time about
170 gallons of liquid pass over, and are condensed in the worm attached to
the apparatus; of this about 150 lbs. are aniline. The temperature should
not exceed 380° F. at any period during the operation. When this is
complete steam is blown in through a tube, in order to sweep out the last
traces of the free aniline, and boiling water is gradually introduced in
quantity sufficient to convert the contents into a homogenous liquid. When
this occurs the liquid is run out of the openings at the bottom into
cisterns provided with agitators; here more boiling water is added, in
the proportion of 300 galls. to every 600 lbs. of crude magenta, and also
6 lbs. of hydrochloric acid. The mass is then boiled for four or five
hours by means of steam pipes, the agitators being kept in constant
motion. The solution of hydrochloride, arsenite, and arseniate of
rosaniline thus obtained is filtered through woollen cloth, and 720 lbs.
of common salt added to the liquid (which is kept boiling) for each 600
lbs. of crude magenta. By this means the whole of the rosaniline is
converted into hydrochloride, which, being nearly insoluble in the strong
solution of arseniate and arsenite of sodium produced in the double
decomposition, separates and rises to the surface; a further quantity is
deposited from the saline solution on allowing it to cool and stand for
some time. In order to purify the crude rosaniline hydrochloride it is
washed with a small quantity of water, redissolved in boiling water
slightly acidulated with hydrochloric acid, filtered, and allowed to
crystallise.”
If in the treatment of aniline with arsenic acid the latter be
considerably beyond the proportion of aniline employed, VIOLET and BLUE
dyes may be formed. The production of such has been patented by Girard and
De Laire.
4. Laurent and Casthélaz have obtained aniline red direct from benzol,
without the preliminary isolation of aniline. Nitrobenzol is treated with
twice its weight of iron finely divided, and half its weight of
concentrated hydrochloric acid. The colouring matter obtained by this
process is said to be inferior in beauty to that procured from aniline.
5. Messrs Renard Brothers include in their patent the ebullition of
aniline with stannous, stannic, mercurous, and mercuric sulphates, with
ferric and uranic nitrates and nitrate of silver, and with stannic and
mercuric bromides.
6. Messrs Dale and Curo’s (patent dated 1860) consists in the treatment of
aniline or hydrochlorate of aniline with nitrate of lead.
7. Mr Smith claims the ebullition of aniline with perchloride of antimony,
or the action of antimonic acid, peroxide of bismuth, stannic, ferric,
mercuric, and cupric oxides, upon hydrochlorate or sulphate of aniline, at
the temperature of 180°.
Coupier’s process for the manufacture of magenta without the use of
arsenic acid is as follows:——He heats together pure aniline, nitrotoluene,
hydrochloric acid, and a small quantity of finely-divided metallic iron,
to a temperature of about 400° F. for several hours. The pasty mixture
soon solidifies to a friable mass resembling crude aniline red——ordinary
commercial aniline. The above processes are for the preparation of crude
aniline red only. The crude colours contain some undecomposed aniline,
mostly in the form of salts. They are also contaminated with tarry
matters, some insoluble in water and dilute acids; others soluble in
bisulphide of carbon, naphtha, or in caustic or carbonated alkalies. If,
therefore, the crude red be boiled with an excess of alkali the
undecomposed aniline is expelled, the acid which exists in the product
being fixed. On treating the residue with acidulated boiling water the red
is dissolved, while certain tarry matters remain insoluble. If now the
boiling solution be filtered, and then saturated with an alkali, the
colouring matter is precipitated in a tolerable state of purity. By
redissolving the precipitated red in an acid, not employed in excess, a
solution is obtained which frequently crystallises, or from which a pure
red may be thrown down by a new addition of chloride of sodium or other
alkaline salt.
Dr Hofmann and Mr Nicholson have demonstrated that pure aniline, from
whatever source obtained, is incapable of furnishing a red dye, but that
it does so when mixed with its homologue toluidine——toluidine by itself
being equally incapable of yielding it. From this it will be evident that
an aniline rich in toluidine is an essential condition for obtaining
aniline red.
Magenta consists of brilliant large crystals, having a beautiful
golden-green metallic lustre, and soluble in water to an intense
purplish-red solution. It is a salt of a colourless base, rosaniline,
which is prepared from magenta by boiling with hydrate of potassium, and
allowing the solution to cool, when it crystallises out in colourless
crystals, having the formula C_{20}H_{19}N_{3}H_{2}O. All the salts of
rosaniline have a splendid purple-red colour, and that usually met with as
magenta is the hydrochlorate, although the nitrate, oxalate, and acetate
are also to be obtained.
Sugar, previously dyed with magenta, is sometimes used as an adulterant of
crystallised magenta. If present, the larger crystals of dyed sugar may be
readily detected by their colour being paler at the edges, when the
suspected sample is spread out on a sheet of white paper in the sunshine.
One of the best methods of testing magenta is to make a comparative dyeing
experiment with the sample under examination, and with one of known
purity, using white woollen yarn.
From magenta or hydrochlorate of rosaniline a large number of colouring
matters are produced, the most important of which will be briefly
described below.
ANILINE BLACK. “Dissolve 20 parts of potassium chlorate, 40 parts of
sulphate of copper, 16 parts of chloride of ammonium, and 40 parts of
aniline hydrochloride, in 500 parts of water, warming the liquid to about
60°, and then removing it from the water bath. In about three minutes the
solution froths up and gives off vapours which strongly attack the
breathing organs. If the mass does not become quite black after the lapse
of a few hours it is again heated to 60°, and then exposed in an open
place for a day or two, and afterwards carefully washed out till no salts
are found in the filtrate. For use in printing, the black paste is mixed
with a somewhat large quantity of albumen, and the goods after printing
are strongly steamed. The paste can be pressed into moulds, and used as a
substitute for Indian ink.” (A. Müller.) “Mix equal weights of aniline
(containing toluidine), hydrochloric acid, and potassium chlorate, with a
minute quantity of cupric chloride and a sufficient quantity of water, and
leave the mixture to evaporate spontaneously, when a black powder will be
obtained.” (Rheineck.)
ANILINE BLUE, or BLEU DE LYONS. This dye is prepared by heating a mixture
of magenta, acetate of sodium, and aniline in iron pots, provided with
stirrers, &c., in an oil bath, to 370° Fahr. (190° C.), and the excess of
aniline distilled over. When a good blue has been obtained the heat is
removed, and the thick treacly fluid purified. This is effected for the
commoner varieties by treating the crude product with hydrochloric acid,
to dissolve all the excess of aniline, and the various red and purple
impurities; but for the better qualities by mixing the crude product with
methylated spirit, and pouring the whole into water acidulated with
hydrochloric acid, and then thoroughly washing the colouring matter that
is precipitated, with water and drying.
This blue, like magenta, is a salt of a colourless base, which
has been named Triphenyl-rosaniline. C_{38}H_{31}N_{3}, or
C_{20}H_{16}(C_{6}H_{5})_{3}N_{3}. Aniline blue, or Lyons blue, is sent
into the market either as a coarse powder of a coppery lustre, or in
alcoholic solution; as it is insoluble in water, which necessitates it
being added to the dye bath in solution in spirit, a great drawback.
Mr Nicholson, by treating Lyons blue in the same manner as indigo is
converted into sulphindigotic acid, has succeeded in rendering it soluble;
dissolving in alkalies to form colourless salts, and decomposed by acids
into its original blue colour.
By a modification of this method ‘NICHOLSON’S BLUE’ is prepared, a fine
soluble blue dye. Another colouring matter called Paris blue or bleu de
Paris was obtained by heating stannic chloride with aniline for 30 hours
at a temperature of 356° Fahr. (180 C.). It is a fine pure blue, soluble
in water, and crystallising in large blue needles with a coppery lustre.
Another method pursued in manufacture of this colour on a large scale is
carried out by allowing a mixture of a salt of rosaniline, with an excess
of aniline, to digest at a temperature of 150° to 160° for a considerable
time. If a mixture of 2 kilogrammes of dry hydrochlorate of rosaniline,
and 4 kilogrammes of aniline be employed, the operation is completed in
four hours. The crude blue is purified by treating it successively with
boiling water, acidulated with hydrochloric acid, and with pure water,
until it is of the purest blue colour. ‘Nicholson’s blue’ is obtained by
digesting triphenyl rosaniline——mono-sulphonic acid (made by dissolving
triphenyl rosaniline hydrochloride in strong sulphuric acid, and heating
the solution for five or six hours. On the addition of water, the acid is
obtained as a dark blue precipitate, and dried at 100°), with a quantity
of soda-lye not quite sufficient for saturation, filtering the solution
and evaporating. It is dried at 100°. Wool dipped into a hot aqueous
solution of Nicholson’s blue, especially if borax or water-glass be added,
extracts it in a colourless state, and holds it so fast that it cannot be
washed out with water, but on dipping the wool thus prepared into an acid
the salt is decomposed, and the colouring matter is set free.
ANILINE BLUE FOR PRINTING. Blumer-Zweefel gives the following
process:——“Mix 100 parts of starch with 1000 parts of water, and add to it
while warm 40 parts of potassium chlorate, 3 to 4 parts of ferrous
sulphate, and 10 parts of sal ammoniac. The well-mixed paste, when quite
cold, is mixed with 70 parts of aniline hydrochloride, or an equivalent
quantity of tartrate, and immediately used. The printed goods are
oxidised, then passed through warm or faintly alkaline water, whereby the
blue colour is developed.”
VIOLET IMPERIAL. If the action of the aniline and magenta in the process
of manufacturing aniline blue be stopped before it is finished, and the
resulting product treated with dilute acid, a colouring matter called
violet imperial is obtained. It is now, however, replaced by the Hofmann
violets.
Mr Nicholson obtains another violet from aniline red, by heating it in a
suitable apparatus to a temperature between 200° and 215° C. The resulting
mass is exhausted with acetic acid, and the deep-violet solution diluted
with enough alcohol to give the dye a convenient strength. Aniline violet,
although it resists the action of light to a very considerable extent, has
been shown by Chevreul to be inferior in this particular than either
madder, cochineal, or indigo.
HOFMANN VIOLETS. On a large scale these violets are produced in deep
cast-iron pots, surrounded by a steam jacket, and provided with a lid,
having a perforation for distilling over the excess of reagents.
These vessels are charged with a solution of magenta in methylated or wood
spirit, and iodide of ethyl or methyl, in proportions according to the
shade required, and the whole heated by steam for five or six hours, when
the excess of alcohol and iodide of ethyl is distilled over. The resulting
product is dissolved in water, filtered, precipitated with common salt,
and well washed.
Like most of the other colours, Hofmann violets are salts of colourless
bases. That of a red shade has a formula of C_{22}H_{23}N_{3}, or
C_{20}H_{18}(C_{2}H_{5})N_{3}; of a true violet shade C_{24}H_{27}N_{3},
or C_{20}H_{17}(C_{2}H_{5})_{2}N_{2}; and of a blue shade of violet, of
C_{26}H_{31}N_{3}, or C_{20}H_{16}(C_{2}H_{5})_{3}N_{3}. They are all
moderately fast on wool and silk, although less so on cotton, and, as they
can be produced in nearly every shade of violet, are in great use, having
replaced most of the other violets.
The following processes have also been proposed for the production of
aniline violet:
1. Oxidation of an aniline salt by means of a solution of permanganate of
potassium. (Williams.)
2. Oxidation of an aniline salt by means of a solution of ferricyanide of
potassium. (Smith.)
3. Oxidation of a cold and dilute solution of hydrochlorate of aniline, by
means of a dilute solution of chloride of lime. (Bolley, Beale, and
Kirkmann.)
4. Oxidation of a salt of aniline by means of peroxide of lead under the
influence of an acid. (Price.)
5. Oxidation of a salt of aniline in an aqueous solution of peroxide of
manganese. (Kay.)
6. Oxidation of a salt of aniline by free chlorine or free hypochlorous
acid. (Smith.)
DAHLIA. This is prepared from mauve and iodide of ethyl, in the same
manner as the Hofmann violets, and is a purple-red violet. It is a good
colour, but the expense precludes its general use.
BRITANNIA VIOLET. This is obtained in the same manner as the Hofmann
violets, by acting on an alcoholic solution of magenta, with a thick,
viscid, oily fluid of the formula C_{10}H_{15}Br_{3}, obtained by
cautiously acting with bromine on oil of turpentine. It is a beautiful
violet, capable of being manufactured of every shade, from purple to blue,
and most extensively used.
ALDEHYDE GREEN. Prepared by dissolving one part of magenta in three parts
of sulphuric acid, diluted with one part of water, adding by degrees one
and a half part of aldehyde, and heating the whole on a water bath until a
drop put in water turns a fine blue. It is then poured into a large
quantity of hot water containing three parts of hyposulphite of sodium,
boiled and filtered. The filtrate contains the green, which can either be
kept in solution or be precipitated by means of tannic acid or acetate of
sodium. Like the other colours, this green is a salt of a colourless base,
containing sulphur, the formula of which is not known, and is principally
used for dyeing silk, being very brilliant in both day and artificial
light.
IODIDE GREEN. Produced during the manufacture of the Hofmann colours, and
is now used for dyeing cotton and silk; its colour being bluer than that
of aldehyde green, it is more useful. Iodide green, not being precipitated
by carbonate of sodium, is usually sold in alcoholic solution.
PERKINS GREEN. This is also a magenta derivative, and a salt of a powerful
colourless base. It resembles the iodide green, but is precipitated by
alkaline carbonates and picric acid. This colour is used chiefly for
calico printing, and is quite as fast as the Hofmann colours.
ANILINE GREEN. When treated with chlorate of potassium, to which a
quantity of hydrochloric acid has been added, aniline assumes a rich
indigo-blue colour. The same result occurs if the aniline be treated with
a solution of chlorous acid. Similar blues have been obtained by Messrs
Crace Calvert, Lowe, and Clift. Most of these blues possess the property,
when subjected to the action of acids, of acquiring a green tint, called
EMERALDINE. Dr Calvert obtained this colour directly upon cloth, by
printing with a mixture of an aniline salt and chlorate of potassium, and
allowing it to dry. In about twelve hours the green colour is developed.
This colour may be converted into blue by being passed through a hot
dilute alkaline solution, or through a bath of boiling soap.
ANILINE YELLOW. Amongst the secondary products obtained during the
preparation of aniline red, there occurs a well-defined base of a splendid
yellow colour, to which the name _chrysaniline_ has been given. It is
prepared by submitting the residue, from which the rosaniline has been
extracted, to a current of steam for some time, when a quantity of the
chrysaniline passes into solution. By adding nitric acid to the solution,
the chrysaniline is thrown down in the form of a difficultly soluble
nitrate. The intimate relation between chrysaniline, rosaniline, and
leucaniline has been shown by Hofmann.
Chrysaniline C_{20}H_{17}N_{3}.
Rosaniline C_{20}H_{19}N_{3}.
Leucaniline C_{20}H_{21}N_{3}.
SAFFRANINE. This dye stuff is of a bright red-rose colour. Mené says it
may be prepared commercially by treatment of heavy aniline oils
successively with nitrous and arsenic acids; or two parts of the aniline
may be heated with one of arsenic acid, and one of an alkaline nitrate for
a short time, to 200° or 212° F. The product is extracted with boiling
water, neutralised with an alkali, filtered, and the colour thrown down by
common salt.
Besides the above products obtained from aniline, a series of colours have
been obtained from phenol, or carbolic acid, another substance obtained
from coal tar.
PICRIC ACID. This is obtained by treating in a suitable apparatus, with
proper precautions, carbolic acid with nitric acid. It is a pale yellow
crystalline acid, forming dark orange explosive salts, and dyeing silk a
fine yellow.
ISOPURPURATE OF POTASSIUM. GRENATE BROWN. GRENATE SOLUBLE. By treating
picric acid with cyanide of potassium a very explosive salt is obtained,
used to dye wool a dark maroon colour.
AURINE, or ROSOLIC ACID. This is obtained by heating a mixture of
sulphuric, oxalic, and carbolic acids, and purifying the products. It is
a beautiful reddish, resinous substance, with a pale green lustre, and
yielding an orange coloured solution, changed by alkalies to a splendid
crimson. Owing to the difficulty in using it, however, it is not very
extensively employed.
PEONINE, or CORALLINE. This dye is formed when rosolic acid and ammonia
are heated to between 248° and 284° Fahr. (120° to 140° C.). It is a fine
crimson dye, forming shades similar to safflower on silk, but, owing to
the bad effects of acids, not much used.
AZULINE. Prepared by heating coralline and aniline together. A coppery
coloured resinous substance, soluble, in alcohol, and with difficulty in
water, and dyeing silk a blue colour. The aniline blues, however, have
superseded it to a great extent.
There are other substances obtained from coal tar that have been employed
to form dyes, but of which we shall only refer to one——naphthaline. By
treating this in exactly the same manner as benzol, it is converted into
aniline. A solid crystalline white base, termed naphthylamine, is
produced. From this substance is obtained the following dye.
DINITRONAPHTHAL, or MANCHESTER YELLOW. Naphthylamine is converted into
diazynaphthol by treatment with nitrate of potassium, and the latter, when
heated with nitric acid, yields the colour. It is a weak acid, and the
salt employed in commerce is the beautiful yellow crystalline calcium salt
which dyes silk and wool a magnificent golden-yellow colour.
=TARPAU′LIN.= _Syn._ TARPAWLING. Canvas covered with tar or any
composition to render it waterproof.
=TAR′RAS.= _Syn._ TERRAS. A volcanic product resembling puzzolano, that
imparts to mortar the property of hardening under water. Several other
argillo-ferruginous minerals possess the same power, and are used under
this term.
=TAR′TAR.= _Syn._ ARGAL, ORGOL; TARTARUM, TARTARUS, L. Impure bitartrate
of potassa. Crude tartar is the concrete deposit formed upon the sides of
the casks and vats during the fermentation of grape juice. That obtained
from white wine is white argol; that from red wine, red argol. After
purification it forms cream of tartar.
=Tartar, Ammo′′niated.= _Syn._ AMMONIO-TARTRATE OF POTASSA, SOLUBLE TARTAR
(Ammoniated); TARTARUS AMMONIATUS, TARTARUM SOLUBILE AMMONIATUM, L.
_Prep._ Neutralise a solution of cream of tartar with ammonia in slight
excess, then evaporate, and crystallise. Very soluble in water. A
favourite laxative on the Continent.
=Tartar, Bo′′raxated.= _Syn._ SOLUBLE CREAM OF TARTAR, BORO-TARTRATE OF
POTASSA AND SODA; TARTARUM BORAXATUM, CREMOR TARTARI SOLUBILIS, POTASSÆ ET
SODÆ TARTRAS BORAXATA, L. _Prep._ From borax, 2 lbs; cream of tartar, 5
lbs. (both in powder); dissolved in water, evaporated, and crystallised.
See POTASSIUM BOROTARTRATE.
=Tartar, Chalybea′ted.= Potassio-tartrate of iron.
=Tartar, Cream of.= Bitartrate of potassa.
=Tartar, Emet′ic.= Potassio-tartrate of antimony.
=Tartar, Oil of.= Deliquesced carbonate of potassa.
=Tartar, Reduced.= _Syn._ CREMOR TARTARI REDUCTUS, L. An article is sold,
under the name of ‘British cream of tartar,’ which contains 1/4 its weight
or more of bisulphate of potassa.
=Tartar, Salt of.= Carbonate of potassa.
=Tartar, Sol′uble.= Neutral tartrate of potassa.
=Tartar, Spirit of.= Pyrotartaric acid.
=TARTAR′IC ACID.= H_{2}C_{4}H_{4}O_{6}. _Syn._ ACID OF TARTAR, ESSENTIAL
SALT OF T.†; ACIDUM TARTARICUM (B. P., Ph. L., E., & D.), SAL ESSENTIALE
TARTARI†, L. _Prep._ 1. (Ph. L. 1836.) Take of cream of tartar, 4 lbs.;
boiling water, 2 gall.; dissolve by boiling; add, gradually, of prepared
chalk, 12 oz. 7 dr. (made into a milk with water), and, when the
effervescence ceases, add another like portion of prepared chalk,
dissolved in hydrochloric acid, 26-1/2 fl. oz., or q. s., diluted with
water, 4 pints; collect the precipitate (‘tartrate of lime’), and, after
well washing it with water, boil it for 15 minutes in dilute sulphuric
acid, 7 pints and 17 fl. oz.; next filter, evaporate the filtrate (to the
density of 1·38), and set it aside to crystallise; redissolve the crystals
in water, concentrate the solution by evaporation, and recrystallise a
second and a third time. The Edinburgh formula is nearly similar. In the
Ph. L. & D. tartaric acid is placed in the Materia Medica.
2. (Gatty.) The solution of argol or tartar is first neutralised with
carbonate of potassa, and to every 300 gall. of the clear liquid, at 5°
Twaddell, 34 gall. of milk of lime (1 lb. of lime per gall.) are added;
carbonic acid gas is then forced in, with agitation; decomposition ensues,
with the formation of ‘bicarbonate of potassa’ and ‘tartrate of lime,’ the
last is converted into tartaric acid in the usual manner, and the former
is evaporated in iron pans, and roasted in a reverberatory furnace for its
potassa.
_Prop._ Tartaric acid forms inodorous, scarcely transparent, oblique
rhombic prisms, more or less modified, which are permanent in the air; it
possesses a purely sour taste, dissolves in about 2 parts of water at 60°
Fahr., and in about its own weight of boiling water; it is slightly
soluble in alcohol; the aqueous solution exhibits right-handed
polarisation, and suffers gradual decomposition by age.
It is free from colour; is entirely, or almost entirely, dissipated by
ignition; and is entirely soluble in water.
_Tests._ 1. Tartaric acid is known to be such by its solution giving white
precipitates with solutions of caustic lime, baryta, and strontia, which
dissolve in excess of the acid.——2. A solution of potassa causes a white
granular precipitate of cream of tartar, soluble by agitation in excess of
the precipitant.——3. Nitrate of silver and acetate of lead give white
precipitates, which, when heated, f nine, and yield the pure metal.——4. If
to a solution of tartaric acid, or a tartrate, solution of a ferric or
aluminum salt be added, and subsequently ammonia or potassa, no
precipitate is formed.——5. At about 570° Fahr. all the tartrates are
blackened, and yield a peculiar and characteristic odour.
_Uses, &c._ Tartaric acid is chiefly employed in calico printing, and, in
medicine, as a substitute for citric acid and lemon juice in the
preparation of cooling drinks and saline draughts. For the latter purpose,
bicarbonate of soda is the alkaline salt commonly employed.——_Dose_, 10 to
30 grains.
_Concluding Remarks._ On the large scale the decomposition of the tartar
is usually effected in a copper boiler, and that of the tartrate of lime
in a leaden cistern. This part of the process is often performed by mere
digestion for a few days, without the application of heat. Leaden or
stoneware vessels are used as crystallisers. Good cream of tartar requires
26% of chalk and 28·5% of dry chloride of calcium for its perfect
decomposition. Dry tartrate of lime requires 75% of oil of vitriol to
liberate the whole of its tartaric acid. A very slight excess of sulphuric
acid may be safely, nay, advantageously, employed. Some manufacturers
bleach the coloured solution of the first crystals by treating it with
animal charcoal; but for this purpose the latter substance should be first
purified by digesting it in hydrochloric acid, and afterwards by
edulcorating it with water, and exposing it to a dull red heat in a
covered vessel. The general management of this manufacture resembles that
of citric acid. To obtain a large product, care must be taken that the
whole of the tartrate of lime be thoroughly decomposed, a matter not
always effected by clumsy manipulators, who do not adapt their quantities
or practice to the circumstances before them.
=TAR′TRATE.= A salt of tartaric acid.
=TARTS.= These may be regarded as miniature pies, consisting of fruit,
either fresh or preserved, baked or spread on puff-paste.
=TARTS.= To make an apple tart take about 2 lbs. of apples, peel them, cut
each into four pieces, and remove the cores; then let each of the quarters
be subdivided into two or three pieces, according to the size of the
apple. Having done this, put half the pieces into a pie-dish, press them
evenly down, and sprinkle over them two ounces of brown sugar; then add
the remaining apples, and afterwards another 2 oz. of sugar, so that the
apples shall form a kind of dome, the centre of which is about two inches
above the sides, now add a wineglassful of water, and cover the top over
with short paste. Let bake in a moderately heated oven from half to three
quarters of an hour.
The quantity of sugar must depend upon the quality, and the degree of
sweetness, or the reverse, of the apples used. If they are of the sweet
kind or very ripe, use less sugar, but a double quantity of water; in the
latter case a little of the juice of lemon will improve the flavour.
Chopped lemon-peel, or cinnamon, or cloves, may also be added to the tart
with advantage.
On making green rhubarb or greengage tarts it will be necessary to use a
little more sugar, and to proceed as for apple tart, taking care, however,
to omit the lemon juice and peel, cinnamon, or cloves. Tarts of ripe
currants, raspberries, cherries, damsons, and mulberries, may be made in
the same manner as rhubarb tart. Pink rhubarb does not require peeling.
=TAU′RIN.= C_{2}H_{7}NSO_{3}. Obtained when purified bile is boiled for
some hours with an excess of hydrochloric acid. By filtration,
evaporation, and dissolving the dry residuum in about 6 parts of boiling
alcohol, nearly pure taurin crystallises out as the solution cools. It
forms with crystalline needles, which are soluble in water, and sparingly
soluble in alcohol. It is remarkable for containing fully 25% of sulphur.
=TAUROCHOLAL′IC ACID.= See CHOLEIC ACID.
=TAW′ING.= In the preparation of the TAWED LEATHER used for gloves,
housings, &c., the skins are first soaked, scraped, and hung in a warm
room until they begin to exhale an ammoniacal odour, and the wool readily
comes off; they are then de-haired, and soaked in water with some
quicklime for several weeks, the water being changed two or three times
during that period; they are then again beamed, smoothed, and trimmed,
after which they are rinsed, and resoaked in a vat of bran-and-water,
where they are kept in a state of gentle fermentation for some weeks (in
this state they are called ‘pelts’); the skins are next well worked about
in a warm solution of alum and salt, again fermented in bran-and-water for
a short time, and are then stretched on hooks, and dried in a stove-room;
they are, lastly, again soaked in water and trodden or worked in a pail or
tub containing some yolks of eggs beaten to a froth with water, after
which they are stretched and dried in a loft, and are smoothed with a warm
smoothing-iron. Sometimes the process is shortened by soaking the skins in
the following mixture after the first steep with bran:——Common salt, 3-1/2
lbs.; alum, 8 lbs.; boiling water, q. s.; dissolve, add of wheaten flour,
21 lbs.; yolks of 9 dozen eggs; make a paste. For use, a portion is to be
largely diluted with water.
CHAMOIS or SHAMMY LEATHER is generally prepared from either sheep or
doe-skins, which, after dressing, liming, &c., are well oiled on the grain
side, then rolled into balls, and thrown into the trough of the
fulling-mill, where they are beaten for 2, 3, or 4 hours. They are next
aired, and again oiled and fulled, and this is repeated a third time, or
oftener, as circumstances may direct. The oiled skins are then exposed to
a fermenting process, or heating in a close chamber, and are afterwards
freed from redundant oil by being scoured in a weak alkaline lye. They
are, lastly, rinsed in clean water, wrung at the peg, dried, and
‘finished’ at the stretcher-iron.
TAWED LEATHER differs from TANNED LEATHER in yielding size or glue under
the influence of heat and moisture, in nearly the same way as the raw
skins.
=TAXIDERMY, Practical.= The following review on the excellent work on this
subject is from ‘The Bazaar,’ ‘Practical Taxidermy; a manual of
instruction to the amateur in collecting, preserving, and setting up
Natural History Specimens of all kinds. By Montagu Browne.’
“The author of this little book begins at the beginning, and, before
detailing the process of skinning, preserving, and mounting any given
vertebrate, he starts with a chapter on ‘Trapping and Decoying Birds and
Animals.’ In this chapter descriptions are given of various forms of
springs, snare, ‘figure-4 trap,’ clap-net, glade-net, bow-net, and box
trap; and some wrinkles are imparted which may be useful to wildfowl
shooters, to say nothing of gamekeepers, whose livelihood depends on their
success in destroying what they are pleased to regard as ‘vermin.’ Chapter
3 is devoted to ‘Necessary Tools,’ of which not only descriptions, but
figures are given, and those who have no knowledge of taxidermy will
probably be surprised to learn how few tools are really necessary for the
purpose.
“On the subject of preservative soaps and powders, Mr Browne has a good
deal to say, and gives no less than seventeen different receipts. Many of
these, however, are only noticed to be condemned, for the author has been
a great experimentalist, and has tested the efficiency or otherwise of all
the preparations he names, with a view of ascertaining the best, and at
the same time that which is most harmless to the operator. For the
preservation of birds he pins his faith to the fourth formula (p. 46),
which is a preservative soap for the inside of the skin, composed of 1-1/2
lb. whiting or chalk, 1 lb. of soft soap, and 2 oz. of chloride of lime,
finely pounded. These ingredients are boiled together in a pint of water,
and the mixture, when properly applied, is said to be so efficacious as to
completely supersede arsenical paste or soap. Presuming that it is used
only for such specimens as are to be immediately cased up in air-tight
cases, nothing further is needed; but as regards such specimens as are
left exposed or uncased, ‘a wash of benzoline liberally applied from time
to time——say twice a year——to the outside,’ is recommended.
“We have long since proved the efficacy of this fluid, not only in
repelling the attacks of moths, and the larvæ of destructive beetles such
as _Dermestes lardarius_, but in killing them in skins that have been
already attacked by them. We can therefore indorse Mr Browne’s remarks,
and may supplement them by a ‘wrinkle’ which he has probably discovered by
this time, although he does not refer to it. It is this. If the amateur in
search of benzoline applies to the nearest chemist for it, he will be
served with the ‘rectified’ fluid, and will be asked three shillings or
three and sixpence for an ordinary medicine bottlefull. If he proceeds,
however, to an oil and colour shop, and asks for it as supplied for
burning in the sponge lamps, he may get a pint for about a tithe of the
cost.
“The best way to apply it is to pour some out in a saucer, saturate a
pinch of cotton wool with it, and dab it on all over the fur or feathers.
The great advantage about it is that, while killing or repelling insects,
it does not in the least injure the specimen to which it is applied. We
have seen a mounted specimen of a bird almost saturated with it, so that
the feathers looked quite draggled; but as soon as the moisture had
evaporated, the feathers all resumed their former shape and glossy
appearance. Care should be taken not to use it by candle light, as the
vapour is inflammable.
“Amongst the seventeen receipts for ‘preservatives’ of different kinds, we
do not see a very simple powder which we have used with success for very
small bird skins, which were almost too delicate to stand the application
of a brush and paste, or soap. It is composed of burnt alum and sugar of
lead, and mixed in the proportion of two thirds of the former to one third
of the latter. The alum dries, the sugar of lead preserves, and if the
specimen while being skinned be dusted with this mixture, it will absorb
all moisture as it arises, for which purpose plaster of Paris is usually
employed. A very little goes a long way, and it is desirable not to apply
too much, lest the astringent nature of the alum should cause the skin to
become brittle and crack.
“Possibly Mr Browne has not referred to this mixture on account of the
poisonous nature of the sugar of lead. He justly remarks that too much
care cannot be exercised in the employment of poisonous preservatives, and
we fully agree with him.
“On the subject of his instructions for skinning birds we have not much
criticism to offer, except perhaps as regards his mode of filling out the
skin after the preservative has been applied, and before the skin is sewn
up. We have found by experience that, after the artificial neck of tow or
cotton wool has been inserted, and the wing bones tied inside, the skin is
much better filled by degrees with little bits of cotton wool inserted
piecemeal, instead of with an artificial body ‘as nearly as possible
shaped to the original body of the bird.’ The advantage of the former plan
is that it is much more quickly executed, and a nice soft skin is the
result, instead of a comparatively hard one. By introducing the wool
piecemeal, too, scarcely any portion of the skin is left without support
on the inside, as is often the case when a ‘made body’ is inserted. This
is material; for if there be any want of inside support at a given point,
pressure upon that point from the outside will cause the skin to crack.
These remarks, however, must be taken to apply only to such specimens as
are intended to be preserved as skins, and are not to be set up.
“Few amateurs, probably, give much time to mounting their specimens, for
they can get them so well done by professional taxidermists, at prices
varying to suit all purses. The art of skinning wild animals and birds,
however, and curing or dressing animal hides, should be acquired by every
sportsman and naturalist who intends to travel and collect and bring home
trophies. To such a one we may specially recommend the chapters which are
devoted to this portion of the subject. In this, as in other respects, Mr
Browne’s book is a ‘practical’ manual of taxidermy.”
=TAXINE.= A poisonous alkaloid present in the leaves and seeds of the yew
(_Taxus faccata_).
=TEA.= _Syn._ THEA, L. The dried leaves of the Chinese tea plants (_Thea
Bohea_ and _Thea viridis_).
It was formerly supposed that BLACK TEAS could only be obtained from _T.
Bohea_, and GREEN TEAS from _T. viridis_, but Fortune and others have
proved that both sorts may be made from either species, and that the
differences in colour and flavour depend chiefly on the age of the leaves
and the treatment they undergo in the drying process. Another species,
named _Thea Assamica_, furnishes ASSAM TEA.
Mulder gives the following as the composition of tea:
Black Green
Tea. Tea.
Essential oil 0·60 0·79
Chlorophyll 1·84 2·22
Wax 0·00 0·28
Resin 3·64 2·22
Gum 7·28 8·56
Tannin 12·88 17·80
Theine 0·46 0·43
Extractive matter 21·36 22·80
Colouring substances 19·19 23·60
Albumen 2·80 3·00
Fibre 28·33 17·80
Ash (mineral substances) 5·24 5·56
Dr Walter Blyth, commenting upon the above, says, the amount of theine is
certainly understated.
_Pur._ The chief adulteration of tea which is extensively practised at the
present day is mixing it with a certain portion of exhausted tea-leaves,
which have been redried and curled. The collection and preparation of
these occupy several hundred persons, chiefly women and children, in and
about London. The leaves which have been found in the possession of the
manufacturers of imitation tea are those of the sloe tree, ash tree, elder
bush, and white thorn. According to Mr Warrington, a most extensive system
of adulterating tea is practised in China. Many samples directly imported
from that country, examined by him, did not contain a single grain of tea,
being made up entirely of other leaves. The ordinary green teas he found,
for the most part, spurious, being manufactured out of the cheaper black
teas. These are ‘faced up’ or ‘painted’ with various colouring substances,
powdered porcelain, clay, &c., which are readily perceived under the
microscope, and even admit of being separated, and chemically examined.
It is a general practice among the grocers in this country to impart what
they call a ‘bloom’ to their green teas by ‘rouncing’ them up with a
little calcined magnesia, or finely powdered talc or French chalk. The
quantity that adheres to the tea is very trifling, but it, greatly
improves its appearance. Black teas are ‘faced,’ in a similar manner, with
finely powdered plumbago or black-lead.
Pure China tea is not turned black by being put into water impregnated
with sulphuretted hydrogen gas, nor does it tinge a solution of ammonia
blue. The infusion is amber-coloured, and is not reddened by the addition
of an acid. The ashes left from the combustion of genuine tea are white,
and do not exceed 5 to 5-1/2%. If they exceed this they may be chemically
examined with the usual tests for alumina, chromate of lead, copper,
cyanide of potassium, gypsum, lime, magnesia, &c. Many of these substances
may be detected by simply agitating the tea with a little cold water, when
they will be detached from its surface, and render the water turbid, or,
by their gravity, sink to the bottom.
Mr A. H. Allen[225] arranges the adulteration of tea under four heads,
giving at the same time directions for their detection:
[Footnote 225: ‘Chemical News,’ xxix, 123, 167, 189, 221; and xxx, 2.]
1. _Mineral additions for increasing weight or bulk_: (_a_) Magnetic
matter. Detected by drawing a magnet under a weighted portion of the tea
spread upon paper, whereby the magnetic matter is separated from the tea
and may be weighed.
(_b_) Siliceous matter. The ash must be estimated by igniting a weighed
portion of the tea. The ash of genuine tea varies from 5·24 to 6·0 per
cent. The ash is then boiled with water, the insoluble part again treated
with hydrochloric acid, and the silica collected and weighed. Genuine tea
does not contain, on an average, more than 0·30 per cent. of ash insoluble
in acid; adulterated teas sometimes contain as much as 10 per cent.
2. _Organic adulterations for increasing weight or bulk_: (_a_) Exhausted
tea leaves. Best detected by estimating the tannin, gum, soluble ash,
insoluble matter, &c.
α. Tannin. 5 gr. of lead acetate are dissolved in 1 litre of water, and
the solution filtered after standing; 5 mgms. of pure potassium
ferricyanide are dissolved in 5 c.c. of water, and an equal bulk of strong
ammonia solution is added. The lead solution is standardised by diluting
10 c.c. to 100 c.c. with boiling water, and adding to it from a burette a
solution of 0·1 pure tannin in 100 c.c. of water, until a few drops, when
allowed to fall through a filter on to a drop of the ferricyanide
solution, spotted on a slab, produce a pink colour. A solution of the tea
is made by repeatedly boiling about 2 grams of the finely-powdered sample
with 80 c.c. of water, until it is completely exhausted. The solution is
filtered and made up to 250 c.c., and used as already described.
The amount of tannin in genuine black tea averages about 10 per cent. A
small quantity of tannin, about 2 per cent., remains in the exhausted
leaves. The percentage of exhausted leaves, E, in a sample may be
estimated, when the per cent. of tannin, T, is known by the equation:
E = (10 - T) / 8 × 100.
β. Insoluble matter is best estimated by boiling the pounded sample
repeatedly with water, and drying the residue at 120° C., until the weight
is constant. The insoluble matter in black tea varies from 46·7 to 53·6
per cent., while in previously infused leaves it varies between 72 to 75
per cent.
γ Gum. The aqueous decoction is evaporated nearly to dryness, the residue
treated with methylated spirit, filtered, washed with spirit, rinsed off
the filter with hot water, the liquid evaporated at a steam heat, weighed,
ignited, and weighed again. The loss represents gum.
δ. Soluble ash. The aqueous solution of the ash is evaporated, _gently_
ignited, and weighed. Genuine tea contains not less than 3 per cent. of
soluble ash, while in exhausted leaves this item falls as low as 0·52 per
cent. If S represents the percentage of soluble ash, the percentage of
exhausted leaves E may be approximately found in the absence of foreign
leaves by the equation:
E = (6 - 2S) × 20.
(_b_) Foreign leaves. The presence of leaves, other than those of the tea
plant, may be detected with some accuracy by estimating the insoluble
matter, tannin, gum, and ash; but the microscope must decide this
question.
[Illustration: Leaves and stalks of best tea brought from China (1861) by
private hand. Natural size. Generally in commercial tea the leaves are
much larger and thicker, and often are cut transversely into two or three
parts. Some stalks and remains of flowers are found in all tea, even the
best.]
[Illustration]
[Illustration: Leaves used in the adulteration of tea——the sloe, willow,
oak, beech, elder, and hawthorn, have been nature-printed and then
lithographed. The drawings of the chloranthus inconspicuus and the
camellia sasanqua, which are said to be used by the Chinese, are copied
from Hassall. The leaves of the elm, poplar, and plane are said to be
sometimes used in England. Falsification with any kind of leaf is,
however, now decidedly uncommon in this country.]
3. _Adulterants for imparting a fictitious strength._ (_a_) Extraneous
tannin matters, such as catechu, &c., are detected by an unusually high
percentage of tannin, as indicated by the lead process. Tea, adulterated
with catechu, gives an infusion which quickly becomes muddy on cooling. 1
gram of the sample and 1 gram of pure tea are each infused in 100 c.c. of
water, and the solutions poured off from the leaves are precipitated,
while boiling, with a slight excess of neutral lead acetate, filtered, and
tested as follows:——About 20 c.c. of the pure tea infusion, when gently
heated with a few drops of silver nitrate, gives a slight cloudiness only;
while tea, containing catechu, gives a copious brownish precipitate, and
the liquid acquires a distinct yellow tinge. One drop of ferric chloride
gives a light green colour if catechu is present, and a greyish-green
precipitate on standing; the solution from pure tea gives a reddish colour
with ferric chloride, due to acetate, and no precipitate on standing.
These tests are applicable only when catechu is present in tolerably large
quantities.
(_b_) Lie tea, when thrown into hot water, falls to powder, because the
gum or starch used to keep it in a compact form is dissolved. The liquid
may be acidified with sulphuric acid, decolourised with permanganate, and
tested for starch. The ash of lie tea is often as high as 30 or 40 per
cent.
(_c_) Caper tea is made into little glossy masses by the aid of gum or
starch; it is usually much adulterated. The insoluble matter is usually
much less than in genuine tea; the gum amounts to 15 or 20 per cent. The
soluble ash often falls below 2 per cent.
(_d_) Soluble iron salts are added to give an appearance of strength by
the formation of tannate of iron. They are detected by shaking the
powdered leaves with cold dilute acetic acid, filtering, and testing for
iron, in the filtrate.
(_e_) Alkaline carbonates are sometimes added to tea. The soluble ash
gives the yellow sodium flame, if sodium salts have been added; the
alkalinity may also be determined in the soluble ash. The average amount
of potash (K_{2}O) in tea is about 1·62 per cent.
4. _Facing and colouring materials._ These may be detected under the
microscope, or the leaves may be washed with warm water, the colouring
matter collected and examined. Indigo is best detected by the microscope;
Prussian blue, by boiling with caustic alkali, filtering, and testing for
ferrocyanide by ferric chloride. The residue, insoluble in alkali, is
fused with alkaline carbonate, evaporated to dryness with hydrochloric
acid; the residue tested for silica, and the filtrate tested for lime and
magnesia.
Moisture varies from 6 to 8 per cent.
Among domestic substitutes for tea are——the leaves of speedwell, wild
germander, black currant, syringa or mock orange, purple-spiked willow
herb, winter green, sweetbriar, cherry tree, sloe, &c., all of which are
used for tea, either singly or mixed. The addition of a single bud of the
black currant to the infusion of ordinary black tea imparts to it a
flavour closely resembling that of green tea.
The brownish-coloured powder vended under the name of ‘la veno beno’ is a
mixture of 2 parts of tea-dust with 5 parts of powdered catechu or terra
japonica. A few grains of this substance thrown into the teapot are
described in the advertisements as being capable of more than doubling the
strength of the beverage.
=Tea, Lie.= Of this compound, Dr Hassall says:——“It is so called because
it is a spurious article and not tea at all. It consists of dust of tea
leaves, sometimes of foreign leaves and sand made up by means of starch or
gum into little masses, which are afterwards painted and coloured, so as
to resemble either black or green gunpowder. The skill exhibited in the
fabrication of this spurious article is very great, and we have met with
at least a dozen varieties of it, differing from each other in the size
and colouring of the little masses.”
The once notorious ‘PARAQUAY PLANT,’ sold in packets, was simply new
meadow-hay that had been wetted with a strong infusion of catechu, then
dried, chopped small, and strongly compressed. See THEINE and CAFFEINE.
=Tea.= “The tea is not a meal; when it is properly used, it should not be
a meal; but it has a special purpose to fulfil, which I will now explain.
Tea——and under the generic term tea I include coffee——tea is usually taken
three hours after dinner. This is the moment which corresponds with the
completion of digestion, when, the food having been conveyed away from the
stomach, nothing remains behind but the excess of the acid juices employed
in digestion, these acid juices create an uneasy sensation at the stomach,
and a call is made for something to relieve the uneasiness; tea fulfils
that object.” “On the same principle, after the business of the
dining-room, the antacid and refreshing beverage, either in the shape of
tea or coffee, is prepared in the drawing-room. In taking either, the
nearer they approach to the simple infusion the better; little milk or
cream, and less sugar, should be the principle. But, seeing the purpose of
tea, how unreasonable to make it the excuse for a meal, to conjoin with it
toast, muffins, bread and butter, and _id genus omne_.” “Three meals a day
may be taken as the standard of habit and custom; tea and coffee having a
specific place and purpose as a beverage, but none as a meal.” (Eras.
Wilson.) See MEALS, &c.
Although tea is undoubtedly prejudicial to children and to adults of
nervous and irritable temperament, there can be no question that, if its
use be not abused, it possesses valuable physiological properties. On the
nervous system it acts as a pleasant stimulant and restorative, its
moderate use not being followed by depression. Dr Parkes says these
effects are in some measure due to the warmth of the infusion. According
to the same authority its use is followed by very little quickening of the
pulse, whilst there is an increase in the amount of perspiration, and a
slightly diminished action on the bowels. Cases, however, are not uncommon
in which this latter effect is reversed.
Dr Edward Smith says that tea increases the excretion of pulmonary
carbonic acid. The contention that the elimination of urea is lessened,
does seem to have been not satisfactorily established. If so, the
diminution is very trifling. Sir Ranald Martin says tea is most useful
against excessive fatigue, especially in hot climates. The traveller in
the Australian bush speaks highly of its renovating effects at the end of
a long day passed in the saddle.
A cup of strong green tea without milk or sugar is a popular and
frequently by no means inefficient remedy for a severe nervous headache.
According to Liebig, tea and coffee resemble soup in their effect on the
system. Lehmann’s experiments seem to show that they lessen the waste of
tissue in the human body. Tea taken too continuously, or in excess,
produces indigestion, flatulence, and constipation, besides rendering its
votaries anæmic and depressed in spirits.
It is a fallacy to suppose that soft water makes the best tea. It
certainly yields a darker infusion than that made from moderately hard
water, but this is owing to the soft water taking up a large quantity of
bitter, physiologically inert, extractive matter from the tea, the
delicate flavour of which becomes thereby greatly impaired. This is why
connoisseurs object to an infusion of too dark a colour. Moderately hard
_boiling_ water, on the contrary, fails to dissolve this objectionable
ingredient, and hence produces a beverage in which the characteristic
taste of the pleasant aromatic principle of the tea is not masked by the
bitter substance. London water, which, when boiled, has a hardness of
about 5 degrees (equal to 5 grains of lime salts to the gallon), makes
excellent tea——better, in fact, than a water of half the hardness, the
latter yielding a slightly bitter infusion. In the use of moderately hard
water, it is essential that it should be allowed to remain on the tea
sufficiently long. The Chinese never employ either very soft or
immoderately hard water, but _a water of medium hardness_.
“Experimentally it is found that infusions of tea and coffee are strong
enough when the former contains 0·6 per cent. of extractive matter, and
the latter 3 per cent., so that a moderate-sized cup (5 oz.) should
contain about 13 grains of the extract of tea, or 66 grains of coffee.
These proportions will be obtained when 263 grains of tea (about 2-1/2
teaspoonfuls) or 2 oz. of freshly-roasted coffee are infused in a pint of
boiling water; and the amounts of the several constituents dissolved are
about as follows:——
“Constituents. Tea. Coffee.
grs. grs.
Nitrogenous matters 17·2 44·0
Fatty matter —— 3·0
Gum, sugar, and extractive 31·7 103·2
Mineral matters 9·1 22·8
———— ——————
Total extracted 58·8 173·0
“So that tea yields, to a pint of fresh water, about 22 per cent. of its
weight, and coffee about 20 per cent. Lehmann found that only 15-1/2 per
cent. of tea was dissolved by water, whereas Sir Humphry Davy estimated it
at 33-1/2 per cent. No doubt the quality of the water, as well as that of
the tea, affects the results, for cold distilled water will extract from
40 to 44 per cent. of black tea, and nearly 50 per cent. of green; but,
for all this, about 22 per cent. is a good average with boiling
water.”[226]
[Footnote 226: Letheby, ‘Lectures on Food.’ Longmans.]
Dr Edward Smith has shown in the following table that, when the usual
custom of measuring tea into the teapot by the spoonful is followed, very
varying weights of tea are employed. Thus he found that the weight of a
spoonful of tea was for——
_Black Teas._
Oolong 39 grains.
Congou (inferior) 52 ”
Flowery Pekoe 62 ”
Souchong 70 ”
Congou (fine) 87 ”
_Green Teas._
Hyson 66 grains.
Twankay 70 ”
Fine Imperial 90 ”
Scented Caper 103 ”
Fine Gunpowder 123 ”
The attempt to make good tea will prove a failure unless the water
employed is _boiling_. Previously to making the infusion, the teapot
should always be warmed up by means of boiling water. The kettle should be
filled from the _tap_, and not the boiler. It should also be borne in mind
that neither good tea nor coffee can be obtained if they are made with
water that has been in the kettle for many hours. The tea is ready to be
drank after the boiling water has stood on it for five minutes.
=Tea, Beef.= _Syn._ INFUSUM CARNIS BUBULÆ, JUSCULUM CUM CARNE BOVIS, L.
This is merely a very concentrated soup formed of lean beef. According to
the common plan, lean beef, 1 lb., is gently simmered in water, 1 quart,
for about 1/2 an hour, when spices, salt, &c., are added, and in a few
minutes the whole is strained for use. The following are other formulæ:
1. (Dr A. T. Thomson.) Take good rump steak, 1/2 lb.; cut it into thin
slices, spread these over a hollow dish, sprinkle a little salt on them,
add a pint of boiling water, and place the dish (covered) near the fire
for 1/2 an hour; then remove the whole to a saucepan, and boil it gently
for 15 minutes; lastly, strain through a hair sieve.
2. (Prof. Liebig.) Beef, free from fat, 1 lb., is to be minced very small,
mixed with an equal weight of cold water, and, after digestion and
agitation in the cold for about 1/2 an hour, heated slowly to boiling;
when it has boiled for a minute or two, strain it through a cloth. It may
be coloured with roasted onion or burnt sugar, and spiced and salted to
taste.
_Obs._ Similar preparations are ordered in some foreign Pharmacopœias from
calves’ lights, crayfish, frogs, mutton, pullets, snails, tortoise, veal,
&c. In the Ph. L. 1746 a form was given for viper broth (JUSCULUM
VIPERINUM). See ESSENCE OF BEEF, EXTRACT OF MEAT, &c.
=TEETH (The).= _Syn._ DENTES, L. An object very subservient to health, and
which merits due attention, is the preservation of the teeth; the care of
which, considering their importance in preparing the food for digestion,
is, in general, far from being sufficiently appreciated. Comparatively
very few persons wash their mouth and clean their teeth even once a day; a
feat which ought always to be practised at the conclusion of a meal, when
either animal food or vegetables are eaten; for the first is apt to leave
behind it a rancid acrimony, and the other an acidity, both of them
hurtful to the teeth. Those who abhor a fetid breath, rotten teeth, and
the toothache, would do well to invariably clean their teeth before
retiring to rest. With smokers, this practice is almost obligatory.
Washing the mouth frequently with cold water is not only serviceable in
keeping the teeth clean, but in strengthening the gums, the firm adhesion
of which to the teeth is of the greatest importance in preserving them
sound and secure. Some persons think it serviceable to add a few drops of
spirit or essence of camphor to the water thus employed, a plan we
certainly approve of. See BREATH, DENTIFRICES, PASTES, POWDERS, TOOTH
CEMENTS, WASHES, &c.
=Teeth, Stoppings for.= See DENTISTRY.
=TEETH′ING.= _Syn._ DENTITION. Children are sometimes born with one or
more teeth; but, in general, the teeth, at birth, consist of mere pulpy
rudiments buried in the gum. Their development is gradual. About the third
or fourth month they begin to assume shape and hardness. At this period
children become fretful, the saliva flows copiously, the gums grow turgid,
and there is a fondness of biting hard cold objects. In nearly all cases
there is more or less fever, frequently a cough or diarrhœa, and a rash
commonly appears, which is called by nurses the ‘red gum.’ These symptoms
generally abate after a fortnight or three weeks, and the child remains
undisturbed until the seventh or eighth month. About this period the gums
again become red, tender, and swollen, and often extremely sensitive, and
painful. The upper part of the gum gradually becomes attenuated and pale,
and, just before the tooth appears, even covered with a blister. These
changes are usually attended by an increased flow of saliva, or
‘drivelling,’ and a lax state of the bowels, both of which are regarded as
favorable symptoms. Sometimes, however, the diarrhœa is excessive, when it
may be cautiously restrained by a dose or two of rhubarb-and-magnesia,
with a little dill or peppermint water; or, better, by the daily use of a
little arrow-root, to which a few drops of pure port wine may be added.
Sometimes the local irritation is considerable, or there are spasms or
convulsions, in which case the practice is to lance the gums. When there
is drowsiness, stupor, or oppressed respiration, one or two leeches may be
applied to the temples, and a small blister to the back of the neck, or
behind the ear. Sluggishness of the bowels may be removed by a little
castor oil; or, when there is actual constipation, by a little calomel or
mercurial powder and rhubarb. Excessive irritability, without other marked
symptoms, is best combated by a drop or two of tincture of hops in
sweetened water. Throughout the whole period of dentition the use of warm
dry clothing, freedom from tight bandages, with thorough ventilation, good
nursing, exercise, fresh air without undue exposure, abundance of crawling
on the carpet, and frequent warm baths, will be found most advantageous.
Indeed, the last, without other treatment, are often sufficient to subdue
the most distressing convulsions and the most obstinate diarrhœa, and in
no case can they do harm. See NURSING, STROPHULUS, &c.
=TELEPHONE.= Within the memory of the present generation Sir Charles
Wheatstone made some experiments on the transmission of sound, which were
subsequently repeated and enlarged upon by Professor Henry in America.
Connecting together by means of a bar of wood the sounding boards of two
pianos placed in houses on opposite sides of the street, Henry found that
when the piano on one side of the street was played upon the musical
sounds it gave out were reproduced by that on the other side. The next
research in this direction was that of Page, in 1837, who, setting up
vibrations in bars of iron, by rapidly magnetising and demagnetising them
elicited from them musical notes corresponding with the velocity of the
vibration. Similar effects, but more marked in character, were produced by
De la Rive, in 1843, by means of a succession of electric currents
transmitted through a copper wire stretched through a cylinder made of
insulated copper wire.
In 1861 Reiss, of Freidrichsdorf, perfected an instrument which, by means
of the vibrations of a diaphragm alternately completing and breaking the
continuity of a galvanic circuit, reproduced musical sounds in an iron bar
at a distance.
Varley, in 1870, obtained similar results to Reiss by the rapid charging
and discharging of a condenser.
In the first of these experiments——viz. Henry’s——the sound was
mechanically conducted along the bar of wood from the strings of one piano
to those of the other, which, being thrown into similar vibratory
movements gave rise to similar sounds.
In the other experiments, on the contrary, the sounds were not due to the
chemical conduction at all, but to currents of electricity. It has been
explained that Reiss’ instrument was capable of reproducing musical sounds
at a distance from their origin. Reiss’ may, therefore, be regarded as the
original telephone. But, although able to reproduce a musical note or
sound originating at a distance, this instrument failed altogether in the
case of a word or a sentence, for the simple reason that the current of
electricity which passes through the wires is an intermittent one. Musical
sounds differ in tone, in intensity, and quality. The tone depends upon
the number of vibrations produced in the air per second; when these are
less than sixteen no sound is produced. The intensity is due to the extent
or amplitude of the vibrations; and the quality or _timbre_, to the form
of the undulations made by the vibrating particles of the atmosphere. Now,
of all these qualities or varieties of sound, the first only, or the tone,
can be reproduced by a current of intermittent electricity, so that Reiss’
is a _tone_ telephone, and as such is only capable of redelivering a
number of musical notes. To Professor A. Graham Bell alone belongs the
merit of having invented an _articulating_ or _speaking_ telephone, or an
apparatus by means of which not only tone, but intensity and _timbre_ of
sound——in short, speech in its entirety can be electrically conveyed from
one point to another, no matter how distant. The practical result of this
is that a conversation can be carried on, the distance by which the
speakers may be separated being of no import. To the particular species of
electricity by which this is accomplished Professor Bell has given the
name ‘undulatory,’ in contradistinction to ‘intermittent’ or ‘pulsatory.’
The annexed plate, which is half the actual size of Bell’s articulating
telephone, represents that instrument in section.
[Illustration]
_m m_ is a permanent bar-magnet, to the upper end of which is attached a
soft iron core, which becomes magnetised by the permanent magnet.
Surrounding the iron core is a coil of very fine insulated copper wire
(_b_), the two ends of which are carried to the terminals (_t t_), by
means of which one is connected with the line wire, and the other with the
earth, _d_ is a disc of thin iron plate, either tinned or japanned, about
the size of a crown piece, and _c_ is the cavity or mouth-piece. Upon
applying the lips to this and speaking into it, the iron disc (_d_)
vibrates towards the soft iron core, the result being that a current of
induced electricity is set up in the coil (_b_), Which, being in
connection by means of the telegraph wire with a precisely similar
arrangement at the other end of the line, reproduces there the spoken
words by means of a corresponding disc. The magnet with its attachments
are enclosed in a wooden case (_a a_, _a a_, _a a_); _n n_ are screws
which secure the iron disk (_b_); _s_ is a screw for adjusting the
distance between the polo of the magnet and the disk (_b_).
The extreme simplicity of Professor Bell’s telephone was the outcome of
several antecedent experiments, worked out by forms of apparatus gradually
diminishing in complexity.
The German physicist Helmholtz had previously shown that by the agency of
a current of intermittent electricity passed through a tuning-fork, he
could produce simultaneous vibrations in a number of other forks connected
with the first by a wire, and that by varying the loudness of these
vibrations by means of resonators, so as to combine the musical notes in
different proportions, the resulting sound was an imitation of certain
vowel sounds, or a copy of the _timbre_ of sound.
Professor Bell’s first telephone was an extension of Helmholtz’s device
for producing vowel or composite sounds. A number of steel wires of
different pitch were made into a harp, and connected by a powerful
permanent magnet, the same arrangement being repeated at the other end of
the circuit. In the magnetic field of the permanent magnet was an
electro-magnet. When a permanent magnet is vibrated in the neighbourhood
of an electro-magnet, this latter will have a current of electricity
generated in it, the intensity of which will vary with the velocity of the
vibrations in the permanent magnet, whilst it will be either positive or
negative according to the direction of these same vibrations. So that a
vowel sound, if produced by causing a number of the rods of the harp to
vibrate at the same time, can be transmitted by a current of electricity,
and will be reproduced by the harp at the other end of the connecting
wire. If a piano were sung into whilst the pedal was down, not only would
the pitch of the voice be echoed back, but an approach to the quality of
the vowel would also be obtained. And theory teaches that if the piano had
a very much larger number of strings to the octave, we should get not only
an approximation to, but an exact vocal reproduction of the vowel. If,
therefore, in the harp there were a large number of steel rods to the
octave, and you were to speak in the neighbourhood of such a harp, the
rods would be thrown into vibration with different degrees of amplitude,
producing currents of electricity, and would throw into vibration the rods
at the other end with the same relative amplitude, and the _timbre_ of the
voice would be reproduced.
The effect when you vibrate more than one of these rods simultaneously is
to change the shape of the electrical undulation, and a similar effect is
produced when a battery is included in the circuit. In this case the
battery current is thrown into waves by the action of the permanent
magnets. Hence you will see that the resultant effect on the current of a
number of musical-tones, is to produce a vibration which corresponds in
every degree to the moving velocity of the air. Suppose, for instance, you
vibrate two rods in the harp, you have two musical notes produced, but of
course if you pay attention to a particle of air, it is impossible that
any particle of air can vibrate in two directions at the same time; it
follows the resultant form of vibration. One curve would show the
vibration of a particle of air for one musical tone, the next one for
another, and the third the resulting motion of a particle of air when both
musical tones are sounded simultaneously. You have by the harp apparatus
the resultant effect produced by a current of electricity, but the same
resultant effect could be produced in the air. There is an instrument
called the phonantograph. It consists of a cone which, when spoken into,
condenses the air from the voice. At the small end of the cone there is a
stretched membrane which vibrates when a sound is produced, and in the
course of its vibration it controls the movement of a long style of wood,
about one foot in length. If a piece of glass with a smoked surface is
rapidly drawn before the style during its movement, a series of curves
will be drawn upon the glass. I myself uttered the vowels _e_, _ay_, _eh_,
_ah_, _aah_. These vowels were sung at the same pitch and the same force,
but each is characterised on the glass by a shape of vibration of its own.
In fact, when you come to examine the motion of a particle of air, there
can be no doubt that every sound is characterised by a particular motion.
It struck me that if, instead of using that complicated harp, and
vibrating a number of rods tuned to different pitches, and thus creating
on the line of wire a resultant effect, we were at once to vibrate a piece
of iron, to give to that piece of iron not the vibration of a musical
tone, but to give it the resultant vibration of a vowel sound, we could
have an undulatory current produced directly, not indirectly, which would
correspond to the motion of the air in the production of a sound.
The difficulty, however, was how to vibrate a piece of iron in the way
required.
The following apparatus gave me the clue to the solution of the problem in
the attempt to improve the phonantograph. I attempted to construct one
modelled as nearly as possible on the mechanism of the human ear, but on
going to a friend in Boston, Dr Clarence J. Blake, an aurist, he suggested
the novel idea of using the human ear itself as a phonantograph, and this
apparatus we constructed together. It is a human ear. The interior
mechanism is exposed, and to a part of it is attached a long style of hay.
Upon moistening the membrane and the little bones with a mixture of
glycerin and water, the mobility of the parts was restored, and on
speaking into the external artificial ear a vibration was observed, and
after many experiments we were enabled to obtain tracings of the vibration
on a sheet of smoked glass drawn rapidly along. This apparatus gave me the
clue to the present form of the telephone. What I wanted was an apparatus
that should be able to move a piece of iron in the way that a particle of
air is moved by the voice.[227]
[Footnote 227: From Professor Bell’s lecture at the Society of Arts, Nov.
28th, 1877, published in the Journal of the Society, vol. 26, p. 17.]
We need not follow Professor Bell through the various stages by which he
arrived at his most successful solution of this problem further than to
state that the simplicity of construction exhibited in the present form of
instrument did not characterise the earlier articulatory telephones.
Amongst the causes contributing to this simplicity may be mentioned the
abandonment of an animal membrane attached to the iron plate, the
diminution of the coil of insulated wire, and the substitution for the
galvanic battery which formerly formed part of the circuit, of the
permanent magnet.
Professor Bell records the curious fact that hardly any difference is
observable in the results by varying the size, thickness, and force of the
permanent magnet, and that beyond a remarkable effect in the quality of
the voice, distinct articulations might be obtained from iron plates of
from 1 inch to 2 feet in diameter and from 1/64th to 1/4th inch in
thickness. With plates of uniform thickness, but of varying diameter, he
obtained the following results. With a plate of small diameter the
articulation was perfectly distinct, but the sound emitted was as if a
person were speaking through the nose. By gradually enlarging the diameter
of the plate this nasal effect as gradually disappeared, until when a
certain diameter was attained a very good quality of voice manifested
itself.
By continuing to enlarge the diameter, a coarse, hollow, drum-like effect
was produced, until when the diameter became very large, the sound
resembled that one hears when the head is inside a barrel, and was
accompanied with a reverberating sound. By reversing the above
conditions——that is, by keeping the diameter constant, and varying the
thickness——it was found that with a very thin plate the drum-like sound
was produced; by gradually increasing the thickness this effect passed
off; then followed distinct articulation, until at a certain increase of
thickness the peculiar nasal quality again developed itself.
In practice it has been found desirable, in establishing speaking
communication between two distant places, to employ two telephones instead
of a single one; one being applied to the mouth and the other to the ear
during a conversation.
With one telephone it was no unusual occurrence for confusion to arise in
consequence of the two speakers talking or listening at the same time.
So faithful is the transmission by the telephone of every variety of
sound, that Mr Preece states, when in telephonic communication with Prof.
Bell, through a quarter of a mile he has heard him “laugh, sneeze, cough,
and, in fact, make any sound the human voice can produce.” It must be
borne in mind, however, that the transmitted speech can only be distinctly
heard in the immediate vicinity of the receiving apparatus; the keenest
hearing fails to detect it at the distance of little more than a foot
away. Hence, when a message is expected, the recipient has to place his
ear to the mouthpiece of the instrument, and use it as an ear-trumpet.
A circumstance tending to impair the satisfactory working of Bell’s
telephone is, that the line wire to which the ends of the coil are
attached becomes inductively affected by the currents of electricity
passing through the parallel and contiguous telegraph wires, the effect,
on a line where there is an active transmission of telegraphic messages,
being that the telephone “emits sounds that are very like the pattering of
hail against a window, and which are so loud as to overpower the effects
of the human voice.”[228]
[Footnote 228: Preece.]
This inconvenience can, however, it is stated, be remedied.
If all the arrangements of the instrument were perfect, there should be no
limits to the distance through which speech could be conveyed by the
telephone. Professor Bell says that in laboratory experiments “no
difficulty has been found in using an apparatus of this construction
through a circuit of 6000 miles;” and that he had found it act efficiently
between New York and Boston, a distance of 258 miles, subject to the
condition that the neighbouring telegraph wires were not in action.
Mr Preece has carried on conversations between Dublin and Holyhead, a
distance of 100 miles.
Two useful applications of the telephone are recorded by Professor Bell,
the one its employment in connection with the diving bell; the other as a
means of communication between those above and below ground in mines. It
has been largely adopted in extensive factories and in commercial houses
both in America and in this country, supplementing, because of its much
greater simplicity and easy application, the electric telegraphs
previously in use in such establishments.
We extract the following from the ‘Journal of the Society of Arts,’[229]
[Footnote 229: Vol. 26, p. 887.]
“THE TELEPHONE AND THE TORPEDO.
“A novel application of the Bell telephone is one which has been made in
connection with torpedoes by Captain C. A. M’Evoy, of 18, Adam Street,
Adelphi. The torpedoes to which the telephone has been applied are those
of the buoyant contact class——that is, floating torpedoes, which are used
for the protection of rivers and harbours. These torpedoes are held in
position beneath the surface of the water by mooring lines and anchors,
and it is necessary to ascertain from time to time that these deadly
agents are in active working order. They are, of course, connected to the
shore by electric wires by which they may be exploded. They are also
arranged so that they may be exploded electrically by contact with passing
vessels. For this latter purpose they are fitted with what is known as a
circuit closer, which is placed in the middle of the charge within the
torpedo. The testing is ordinarily performed by sending a current of
electricity through the torpedo and fuse; but, in order that the fuse may
not be fired, and the torpedo consequently exploded during the process of
testing, an extremely weak current has to be used in connection with a
sensitive galvanometer. The consequence is that the indications received
are so very delicate that they are not always to be relied on. Now, what
Captain M’Evoy does is to supplement the electrical test by the test of
sounds, and to this end he encloses an ordinary Bell telephone in each
torpedo. The telephone is so placed that the vibrating diaphragm is in a
horizontal plane, and upon it are laid a few shot or particles of metal,
and these are boxed in. Every motion of the torpedo causes the shot to
shift their position upon the face of the diaphragm and to cause a slight
noise, which is distinctly heard in the receiving telephone on shore. Thus
each torpedo two or three miles away, in the restless waters of a channel,
is continually telling the operator on shore of its own condition in
language sometimes excited, according to the state of calmness or
agitation of the water at the time. Should the torpedoes be sunk, they
would lie motionless on the bottom, and the silence of the telephone would
indicate the fact of their inoperativeness. The telephones are connected
to the ordinary electric wires of the torpedoes, but this does not prevent
them from being tested in the usual way from the battery on shore.”
=TELLU′RIUM.= A rare greyish-white elementary substance, found only in
small quantities, associated with gold, silver, lead, and bismuth, in the
gold mines of Transylvania. It has often been described as a metal, but is
now commonly classed with the non-metals.
1. Tellurium may be obtained from the bismuth ore (the telluride of
bismuth) by strongly heating the ore with a mixture of carbonate of potash
and charcoal. A potassium telluride is formed which dissolves in water,
forming a solution of a purplish-red colour, from which the tellurium
deposits on exposure of the liquid to the atmosphere.
2. Schrötter gives the following method for the obtainment of metallic
tellurium:——The raw material is treated with dilute hydrochloric acid as
long as carbon dioxide is evolved, then with strong acid until all
sulphuretted hydrogen is driven off.
The liquid is decanted from the residue, which is washed with hydrochloric
acid and hot water, then boiled with aqua regia until the insoluble matter
is white. From the aqua regia solution any gold that may be present is
precipitated by means of ferrous sulphate, and afterwards zinc is added to
precipitate the tellurium. The precipitate on the zinc is washed, dried,
and heated to redness, treated with sulphuric acid to remove any silver,
and the remaining tellurium is then collected.
Tellurium bears a great resemblance to bismuth in appearance, having a
pinkish metallic lustre; it further resembles bismuth in being crystalline
and brittle.
Below a red heat it enters into a state of fusion; at a high temperature
it becomes converted into a yellow vapour. It burns in air, when strongly
heated, with a blue flame having a green rim, and giving off white fumes
that have a peculiar odour. When taken internally, even in very minute
quantities, tellurium imparts to the breath an offensively powerful odour
of garlic. Tellurium dissolves in cold concentrated sulphuric acid, to
which it imparts a rich purple-red colour. If the acid solution be diluted
with water the tellurium precipitates unchanged. There are two oxides of
tellurium: the dioxide (TeO_{2}) and the trioxide (TeO_{3}), the first of
which corresponds to sulphurous, and the second to sulphuric anhydride.
_Tellurous acid_ (H_{2}TeO_{3}) is obtained by pouring a solution of
tellurium on nitric acid of 1·25 into water, when the tellurous acid is
precipitated as a bulky hydrate. This hydrate is slightly soluble in water
and reddens litmus. It forms salts called tellurites.
_Telluric acid_ (H_{2}TeO_{4}). When tellurium or tellurous acid is gently
heated with nitre a potassic tellurate is formed, this being decomposed by
a salt of barium, whilst the resulting barium tellurate is in its turn
decomposed, and the telluric acid separated by sulphuric acid. The
telluric acid occurs in hexagonal prismatic crystals, which, when heated
usually to redness, becoming converted into telluric anhydride, which then
assumes an orange-yellow colour. This telluric anhydride (TeO_{3}) is
entirely insoluble in water, nitric and hydrochloric acids, and alkaline
solutions. Although it has but a feeble attraction for bases, telluric
acid forms salts which are called tellurates. There are two chlorides of
tellurium: the dichloride (TeCl_{2}) and the tetrachloride (TeCl_{4}).
They may both be obtained by the direct action of chlorine on tellurium.
_Telluretted hydrogen, or dihydric telluride_. (H_{2}Te). This compound
presents a striking analogy to seleniuretted and sulphuretted hydrogen.
Like both of these it is gaseous, but resembles the latter in smell more
than the former. It burns with a blue flame, reddens litmus, and when
fused into water forms a colourless solution, which becomes brown by
exposure to the air, owing to the oxidation of hydrogen and the deposition
of tellurmin. The salts of most of the metals are decomposed when a
current of telluretted hydrogen is passed through these solutions, from
which the metals are then thrown down as tellurides. These tellurides
present a close resemblance to the corresponding sulphides. The tellurides
of the alkali metals, like the sulphides, are soluble in water.
_Tests._ The most distinctive character of tellurium compounds is the
reddish-purple solution of potassium telluride they furnish when fused
with potassic carbonate and charcoal and treated with water.
=TEM′PERATURE.= In English pharmacy it is customary to measure the degree
of heat by Fahrenheit’s thermometer. When a boiling heat is directed, 212°
is meant. A gentle heat is that which is denoted by any degree between 90°
and 100° Fahr.
Whenever specific gravity is mentioned, the substance spoken of is
supposed to be of the temperature of 62° Fahr. (Ph. L.)
In the B. P., Ph. E., & D., and in chemical works in this country
generally, the specific gravities of bodies are taken at, or referred to,
the temperature of 60° Fahr. See THERMOMETERS.
The following data may be of use to the pharmacist:
_Degree of Fahr._
2786 Cast iron melts (Daniell).
2016 Gold melts (Daniell).
1996 Copper melts (Daniell).
1873 Silver melts (Daniell).
1750 Brass (containing 25% of zinc) melts (Daniell).
1000 Iron, bright cherry red (Poillet).
980 Red heat, visible in daylight (Daniell).
941 Zinc begins to burn (Daniell).
773 Zinc melts (Daniell).
644 Mercury boils (Daniell), 662 (Graham).
640 Sulphuric acid boils (Marignac), 620 (Graham).
630 Whale oil boils (Graham).
617 Pure lead melts (Rudberg).
600 Linseed oil boils.
518 Bismuth melts (Gmelin).
442 Tin melts (Crichton).
380 Arsenious acid volatilises.
356 Metallic arsenic sublimes.
315 Oil of turpentine boils (Kaure).
302 Etherification ends.
257 Saturated sol. of sal ammoniac boils (Taylor).
256 Saturated sol. of acetate of soda boils.
239 Sulphur melts (Miller), 226 (Fownes).
238 Saturated sol. of nitre boils.
221 Saturated sol. of salt boils (Paris Codex).
220 Saturated sol. of alum, carb. soda, and sulph. zinc, boil.
218 Saturated sol. of chlorate and prussiate potash, boil.
216 Saturated sol. of sulph. iron, sulph. copper, nitrate of lead, boil.
214 Saturated sol. of acetate lead, sulph. and bitartrate potash, boil.
213 or (213·5) Saturated sol. of water begins to boil in glass.
212 Water boils in metal, barometer at 30°.
211 Alloy of 5 bismuth, 3 tin, 2 lead, melts.
201 Alloy of 8 bismuth, 5 lead, 3 tin, melts (Kane).
207 Sodium melts (Regnault).
145 White of egg begins to coagulate.
185 Nitric acid 1·52 begins to boil.
180 (about) Starch forms a gelatinous compound with water.
176 Rectified spirit boils, benzol distils.
173 Alcohol (sp. gr. ·796 to ·800) boils.
151 Beeswax melts (Kane), 142 (Lepage).
150 Pyroxylic spirit boils (Scanlan).
141·8 Chloroform, and ammonia of ·945, boil.
44·5 Potassium melts (Bunsen).
132 Acetone (pyroacetic spirit) boils (Kane).
122 Mutton suet and styracin melt.
116 Bisulphuret of carbon boils (Graham).
115 Pure tallow melts (Lepage), 92 (Thomson).
112 Spermaceti and stearin of lard melt.
111 Phosphorus melts (Miller).
98 Temperature of the blood.
95 Ether (·720) boils.
95 Carbolic acid crystals become an oily liquid.
88 Acetous fermentation ceases, water boils _in vacuo_.
77 Vinous ferm. ends, acetous ferm. begins.
64·4 Oil of anise liquefies.
59 Gay Lussac’s _Alcoomètre_ graduated at.
55 Syrups to be kept at (P. L.).
30 (about) Olive oil becomes partially solid.
32 Water freezes.
·5 Cold produced by snow 2 parts and salt 1 part.
-37·9 Mercury freezes.
=TENT.= A piece of lint, or compressed sponge, used to dilate openings,
wounds, &c.
=TERBIUM.= A rare metal found by Prof. Mosander, associated with erbium
and yttrium in ordinary yttria. See ERBIUM and YTTRIUM.
=TER′RA.= [L.] Earth. TERRA JAPONICA, catechu; TERRA PONDEROSA, sulphate
of baryta, &c.
=TER′RA COT′TA.= Literally, baked clay; a term applied to statues,
architectural ornaments, &c., made of pure white clay, fine sand, and
powdered potsherds, slowly dried, and baked to a strong hardness.
=TEST.= _Syn._ REAGENT. Any substance employed to determine the name or
character of any other substance, or to detect its presence in compounds.
=TEST SOLUTIONS.= The test solutions here given are those of the British
Pharmacopœia, which are used for determining the strength of various
Pharmacopœial preparations by volumetric analysis. In the Pharmacopœia it
is stated: The processes for volumetric estimations may be performed
either with British or with metrical weights and measures, and the
solutions are so arranged that they will be of the same strength, and the
same indications will be obtained in using them, whichever system is
employed, without the necessity of altering any of the figures by which
the quantities of the substances tested or of the test solutions required
in the process are expressed.
According to the British system, the quantities of the substances to be
tested are expressed in grains by weight, whilst the quantities of the
test solutions employed in testing are expressed in grain-measures, the
grain-measure being the volume of a grain of distilled water.
According to the metrical system, the quantities of the substances to be
tested are expressed in grammes by weight, whilst the quantities of the
test solutions employed in testing are employed in cubic centimètres, the
cubic centimètre being the volume of a gramme of distilled water.
As the cubic centimètre bears the same relation to the gramme that the
grain-measure bears to the grain, the one system may be substituted for
the other, with no difference in the results excepting that, by the
metrical system, all the quantities will be expressed in relation to a
weight (the gramme) which is more than fifteen times as great as the
British grain.
In practice it will be found convenient in substituting metrical for
British weights and measures, to reduce the values of all numbers to
one-tenth by moving the decimal points, and this has been done in the
tables appended to the descriptions of the volumetric solutions. The
quantities indicated in the Pharmacopœia, which in grains and
grain-measures can be conveniently used, would be found inconveniently
large if the same numbers of grammes and cubic centimètres were employed.
The following apparatus is required in the preparation and use of these
solutions.
For British weights and measures:
1. A flask, which, when filled to a mark on the neck, contains exactly
10,000 grains of distilled water at 60°. The capacity of the flask is
therefore 10,000 grain-measures.
2. A graduated cylindrical jar which, when filled to O, holds 10,000
grains of distilled water, and is divided into 100 equal parts.
3. A burette. A graduated glass tube which, when filled to O, holds 1000
grains of distilled water, and is divided into 100 equal parts. Each part
therefore corresponds to 10 grain-measures.
For metrical weights and measures:
1. A glass flask which, when filled to a mark on the neck, contains 1
litre, or 1000 cubic centimètres.
2. A graduated cylindrical jar which, when filled to O, contains 1 litre
(1000 cubic centimètres), and is divided into 100 equal parts.
3. A burette. A graduated tube which, when filled to O, holds 100 cubic
centimètres, and is divided into 100 equal parts.
(One cubic centimètre is the volume of one gramme of distilled water at 4°
C.[230], 1000 cubic centimètres equal 1 litre).
[Footnote 230: It is customary to make the measurements with metrical
apparatus at 60° Fahr.]
Volumetric solutions, before being used, should be shaken in order that
they may be throughout of uniform strength. They should also be preserved
in stoppered bottles. All measurements should be made at 60°.
VOLUMETRIC SOLUTION OF BICHROMATE OF POTASH (Bichromate of potash,
KO,2CrO_{3} = 147·5, or K_{2}Cr_{2}O_{7} = 295).
Take of——
Bichromate of potash 147·5 grains.
Distilled water a sufficiency.
Put the bichromate of potash into the 10,000 grain flask, and, having half
filled the flask with water, allow the salt to dissolve; then dilute the
solution with more water, until it has the exact bulk of 10,000
grain-measures: 1000 grain-measures of this solution contain 14·75 grains
of the bichromate (1/10th of K_{2}CrO_{3}, or 1/20th of K_{2}Cr_{2}O_{7}
in grains), and, when added to a solution of a protosalt of iron,
acidulated with hydrochloric acid, are capable of converting 16·8 grains
(1/10th of 6Fe, or 1/20th of 6Fe in grains) from the state of protosalt to
that of persalt grammes, and cubic centimètres may be employed instead of
grains and grain-measures; but for convenience 1/10th of the numbers
should be taken. Thus, 14·75 grammes of bichromate of potash should be
made to form 1000 cubic centimètres of solution. 100 cubic centimètres of
this solution contain 1·475 grammes of the bichromate (1/100th of
KO,2CrO_{3}, or 1/200th of K_{2}Cr_{2}0_{7} in grammes), and, when added
to a solution of protosalt of iron acidulated with hydrochloric acid, are
capable of converting 1·68 grammes of iron (1/100th of 6Fe, or 1/200 of
6Fe, in grammes) from the state of protosalt to that of persalt.
This solution is used for determining the proportion of protoxide of iron
in the following preparations. It is known that the whole of the protosalt
has been converted into a persalt when a minute drop of the liquid, placed
in contact with a solution of red prussiate of potash on a white plate,
ceases to strike with it a blue colour.
British Weights Metrical Weights
and Measures. and Measures.
/-----------/\-------------\ or /---------/\--------\
Grains weight = Grain measures Grams weight = C. C. of
of substance. of vol. sol. of substance. vol. sol.
Ferri arsenias 20 = 170 or 2·0 = 17·0
” carb. sacch. 20 = 330 ” 2·0 = 33·0
” oxid. magn. 20 = 83 ” 2·0 = 8·3
” Phosphas 20 = 250 ” 2·0 = 25·0
VOLUMETRIC SOLUTION OF HYPOSULPHITE OF SODA (hyposulphite
of soda crystallised, NaO_{1}S_{2}O_{2} + 5HO = 124, or
Na_{2}H_{2}S_{2}O_{4}.4H_{2}0 = 248).
Take of——
Hyposulphite of soda, in crystals 280 grains.
Distilled water a sufficiency.
Dissolve the hyposulphite of soda in 10,000 grain-measures of water. Fill
a burette with this solution and drop it cautiously in 1000 grain-measures
of the volumetric solution of iodine until the brown colour is just
discharged. Note the number of grain-measures (_n_) required to produce
this effect; then put 8000 grain-measures of the same solution into a
graduated jar, and augment this quantity by the addition of distilled
water until it amounts to (8000 × 1000) / _n_ grain-measures. If, for
example, _n_=950, the 8000 grain-measures of solution should be
diluted to the bulk of (8000 × 1000) / 950 = 8·421 grain-measures.
1000 grain-measures of this solution contains 24·8 grains of the
hyposulphite (1/10th of 2(NaO,S_{2}O_{2} + 5HO), or 1/10th of
=Na_{2}H_{2}S_{2}O_{4},4H_{2}O= in grains), and therefore corresponds
to 12·7 grains of iodine (1/10th of an equivalent).
Grammes and cubic centimètres may be employed instead of grains and
grain-measures, but for convenience 1/10th of the numbers should be taken.
100 cubic centimètres of this solution contain 2·48 grammes of the
hyposulphite (1/100 of 2(NaO,S_{2}O_{2}+ 5HO), or 1/100th of
Na_{2}H_{2}S_{2}O_{4}.4H_{2}O in grammes), and therefore corresponds to
1·27 grains of iodine (1/100th of an equivalent).
This solution is used for testing the following substances. In each case,
except that of iodine, a solution of iodide of potassium and hydrochloric
acid are added to the substance, and the amount of iodine so liberated is
indicated by this solution:
British Weights Metrical Weights
and Measures. and Measures.
/------------/\------------\ or /---------/\---------\
Grains weight = Grain-measures Grams weight = C. C. of
of substance. of vol. sol. of substance. vol. sol.
Calx Chlorata 10·0 = 850 or 1·00 = 85·0
Iodum 12·7 = 1000 ” 1·27 = 100·0
Liq. calc. chloratæ 60·0 = 500 ” 6·00 = 50·0
Liq. chlori 439·0 = 750 ” 43·90 = 75·0
Liq. Sodæ chloratæ 70·0 = 500 ” 7·00 = 50·0
VOLUMETRIC SOLUTION OF IODINE (iodine, I = 127, or I = 127).
Take of iodine 127 grains.
Iodide of potassium 180 ”
Distilled water a sufficiency.
Put the iodide of potassium and the iodine into the 10,000 grain flask,
fill the flask to about two thirds its bulk with distilled water, gently
agitate until solution is complete, and then dilute the solution with more
water, until it has the exact volume of 10,000 grain-measures. 1000
grain-measures of this solution contain 1/10th of an equivalent in grains
(12·7 grains) of iodine, and therefore correspond to 1·7 grains of
sulphuretted hydrogen, 3·2 grains of sulphurous acid, and 4·95 grains of
arsenious acid.
Grammes and cubic centimètres may be employed instead of grains and
grain-measures, but for convenience 1/10th of the numbers should be taken.
100 cubic centimètres contain 1·27 grammes of iodine, and correspond to
0·17 grammes of sulphuretted hydrogen, 0·32 grammes of sulphurous, and
0·495 grammes of arsenious acid. This solution is for testing the
following substances. It is dropped from the burette into the liquid to be
tested, until free iodine begins to appear in the solution.
British Weights Metrical Weights
and Measures. and Measures.
/------------/\------------\ or /---------/\--------\
Grains weight = Grain-measures Grams weight = C. C. of
of substance. of vol. sol. of substance. vol. sol.
Acid. arsenios 4·0 = 808 or 0·40 = 80·8
Acid. sulphurosum 34·7 = 1000 ” 3·47 = 100·0
Liquor arsenicalis 441·5 = 808 ” 44·15 = 80·8
Liquor arsenici }
hydrochloricus} 441·5 = 810 ” 44·15 = 81·0
VOLUMETRIC SOLUTION OF NITRATE OF SILVER (nitrate of silver, AgO, NO_{5} =
170, or AgNO_{3}* = 170).
Take of nitrate of silver 170 grains.
Distilled water a sufficiency.
Put the nitrate of silver into the 10,000 grain flask, and having filled
half the flask with water, allow the salt to dissolve; then dilute the
solution with more water until it has the exact bulk of 10,000
grain-measures.
The solution should be kept in an opaque stoppered bottle. 1000
grain-measures of this solution contain 1/10th of an equivalent in grains
of nitrate of silver (or 1·70 grains). Grammes and cubic centimètres may
be employed instead of grains and grain-measures, but for convenience
1/10th of the numbers should be taken. 100 cubic centimètres contain
1/10th of an equivalent in grammes of nitrate of silver (or 1·7 grammes).
It is used in testing the following substances.
British Weights Metrical Weights
and Measures. and Measures.
/------------/\------------\ or /--------/\---------\
Grains weight = Grain-measures Grams weight = C. C. of
of substance. of vol. sol. of substance. vol. sol.
Acid. hydrocyan. 270 = 1000 or 27·0 = 100·0
Potass. bromid. 10 = 840 ” 1·0 = 84·0
Sodæ arsenias (dry) 10 = 1613 ” 1·0 = 161·3
VOLUMETRIC SOLUTION OF OXALIC ACID (crystallised oxalic acid, 2HO,
C_{4}H_{6} + 4HO = 126, or H_{2}C_{2}O_{4}2H_{2}O = 126). Take of——
Purified oxalic acid in }
crystals, quite dry, but } 630 grains.
not effloresced }
Distilled water a sufficiency.
Put the oxalic acid into the 10,000 grain flask, fill the flask to about
two thirds of its bulk with water, allow the acid to dissolve, and then
dilute the solution with more water until it has the exact volume of
10,000 grain-measures. 1000 grain-measures of this solution contain half
an equivalent in grains (63 gr.) of oxalic acid, and are therefore capable
of neutralising an equivalent in grains of an alkali or alkaline
carbonate. Grammes and cubic centimètres may be employed instead of grains
and grain-measures, but for convenience 1/10th of the numbers should be
taken. 100 cubic centimètres contain 1/20th of an equivalent in grammes
(6·3 grammes) of oxalic acid, and will neutralise 1/10th of an equivalent
in grammes of an alkali. The following substances are tested with this
solution:
British Weights Metrical Weights
and Measures. and Measures.
/-------/\-------\ or /--------/\--------\
Grains = Grain- Grams = C. C. of
weight of measures weight of vol. sol.
substance. of vol. sol. substance.
Ammoniæ carb. 59·0 = 1000 or 5·90 = 100·0
Borax 191·0 = 1000 ” 19·10 = 100·0
Liq. ammon. 85·0 = 500 ” 8·50 = 50·0
Liq. ammon. fort. 52·3 = 1000 ” 5·23 = 100·0
Liq. calcis 4380·0 = 200 ” 438·00 = 20·0
Liq. calcis sacchar 460·2 = 254 ” 46·02 = 25·4
Liq. plumbi subacet. 413·3 = 810 ” 41·33 = 81·0
Liq. potassæ 462·9 = 482 ” 46·29 = 48·2
Liq. potassæ efferves. 4380·0 = 150 ” 438·00 = 15·0
Liq. sodæ 458·0 = 470 ” 45·80 = 47·0
Liq. sodæ efferves. 4380·0 = 178 ” 438·00 = 17·8
Plumbi acetas 38·0 = 200 ” 3·80 = 20·0
Potassa caustica 56·0 = 900 ” 5·60 = 90·0
Potassæ bicarb. 50·0 = 500 ” 5·00 = 50·0
Potassæ carb. 83·0 = 980 ” 8·30 = 98·0
Potassæ citras 102·0 = 1000 ” 10·20 = 100·0
Potassæ tartras 113·0 = 1000 ” 11·30 = 100·0
Potassæ tartras acida 188·0 = 1000 ” 18·80 = 100·0
Soda caustica 40·0 = 900 ” 4·00 = 90·0
Soda tartarata 141·0 = 1000 ” 14·10 = 100·0
Sodæ bicarb. 84·0 = 1000 ” 8·40 = 100·0
Sodæ carb. 143·0 = 960 ” 14·30 = 96·0
VOLUMETRIC SOLUTION OF SODA (hydrate of soda, NaO, HO = 40, or NaHO = 40).
Take of solution of soda a sufficiency.
Distilled water a sufficiency.
Fill a burette with the solution of soda, and cautiously drop this into 63
gr. of purified oxalic acid, dissolved in about 2 oz. of water, until the
acid is exactly neutralised as indicated by litmus.
Note the number of grain-measures (_n_) of the solution used, and having
then introduced 9000 grain-measures of the solution of soda in a graduated
jar, augment this quantity by the addition of water until it becomes
9000 × 1000 / _n_ grain-measures =
If, for example, _n_ = 930, the 9000 grain-measures should be augmented to
9000 × 1000 / 930 = 9,677 grain-measures.
One thousand grain-measures of this solution contain one equivalent in
grains (40 gr.) of hydrate of soda, and will therefore neutralise one
equivalent in grains of any monobasic acid.
Grammes and cubic centimètres may be employed, instead of grains and
grain-measures; but for convenience 1/10th of the numbers should be taken.
1000 cubic centimètres contain 1/10th of an equivalent in grammes (4
grammes) of hydrate of soda, and will neutralise 1/10th of an equivalent
in grammes of an acid.
This solution is used for testing the following substances:
British Weights Metrical Weights
and Measures. and Measures.
/--------/\-------\ or /--------/\--------\
Grains = Grain- Grams C. C. of
weight of measures weight of = vol. sol.
substance. of vol. substance.
sol.
Acetum 445·4 = 402 or 44·54 = 40·2
Acid. acet. 182·0 = 1000 ” 18·20 = 100·0
Acid. acet. dil. 440·0 = 313 ” 44·40 = 31·3
Acid. acet. glac. 60·0 = 990 ” 6·00 = 99·0
Acid. citric 70·0 = 1000 ” 7·00 = 100·0
Acid. hydrochloric 114·8 = 1000 ” 14·48 = 100·0
Acid. hydrochloric dil. 345·0 = 1000 ” 34·50 = 100·0
Acid. nitric 90·0 = 1000 ” 9·00 = 100·0
Acid. nitric dil. 361·3 = 1000 ” 36·13 = 100·0
Acid. nitro-hydrochlor. dil. 352·4 = 920 ” 35·24 = 92·0
Acid. sulph. 50·6 = 1000 ” 5·06 = 100·0
Acid. sulph. arom. 304·2 = 830 ” 30·42 = 83·0
Acid. sulph. dil. 359·0 = 1000 ” 35·90 = 100·0
Acid. tart. 75·0 = 1000 ” 7·50 = 100·0
=TE′TANUS.= Spasm with rigidity. When it affects the under jaw, it is
called TRISMUS, or locked-jaw; when the body is drawn backward by the
contraction of the muscles, it is called OPISTHOTONOS; when the body is
bent forward, EMPROSTHOTONOS; and when the body is drawn to one side,
PLEUROSTHOTONOS.
The cause of tetanus, in temperate climates, is generally irritation of
the nerves, arising from local injuries, especially punctured or lacerated
wounds. Of these the most trivial are occasionally sufficient to produce
locked-jaw. In hot climates the disease is occasionally produced by
exposure to cold, or by suddenly suppressed perspiration. The last variety
is curable; the former one scarcely ever so. The proper treatment is a
matter still undetermined. Sedatives, antispasmodics, and powerful
stimulants, have each had their advocates. Large doses of wine and
spirits, in conjunction with opium, have occasionally been administered
with success. Electricity and the vapour bath have also proved useful. In
all cases the bowels should be moved by active aperients, either by the
mouth or per anum. Dr Shrimpton[231] recommends the Chinese mode of
treating tetanus, which is as follows:——From four to five grains of solid
opium are mixed with tea-leaves, or dried roses, and carefully beaten
together with molasses. The patient smokes this mixture, and endeavours to
draw the smoke into the lungs, leaving off when the narcotic effects are
produced. These last generally from three to four hours. The same
operation should be repeated whenever there are any signs of returning
spasms.
[Footnote 231: ‘Lancet,’ 1871, vol. ii, page 547.]
=TET′TERS.= The popular name of several cutaneous diseases, the treatment
of which can only be properly undertaken by the experienced medical man.
=THAL′LIUM.= Tl. [Eng., L.] A heavy metal, belonging to the mercury,
silver, and lead group, discovered by Crookes in the early part of 1861,
and displayed by him as “a new metallic element” at the opening of the
International Exhibition, on the 1st of May, 1862. Thallium is a
widely-diffused metal, being found in many minerals, particularly in iron-
and copper-pyrites and native sulphur. It has recently been obtained in
comparatively large quantities from the dust of the flues leading to
sulphuric acid chambers. The spectrum of thallium consists of a single
most characteristic line of a beautiful green colour. The spectrum
produced when the metal is burnt in the electric arc is, however, more
complicated, and consists of several green, blue, and other lines.
Thallium melts at 550° Fahr., and at a less heat may be readily welded, a
property that has hitherto been regarded as peculiar to iron and platinum.
Its specific gravity varies from 11·8 to 11·9, according to the mode of
preparation. When freshly cut it has a dull white colour, destitute of the
brilliancy of polished silver. Exposed to the air, it tarnishes rapidly, a
straw-coloured oxide making its appearance on the surface. The oxide is
alkaline and caustic to the taste, and much more soluble than the oxides
of silver and lead. The metal is remarkable for its strongly marked
diamagnetic characters, resembling bismuth in this respect. The alloys of
thallium are very remarkable. Copper, alloyed with only one half per cent,
of thallium, becomes quite brittle; but the alloy with tin is malleable.
Mr Crookes has prepared a great number of the salts of this interesting
metal. These need not be described here, as they have not yet been applied
to any use in the arts. See SULPHURIC ACID.
=THALLOGENS.= Thallogens or Thallogenous plants are structurally the
simplest of the acotyledonous, or flowerless plants, consisting simply of
a collection of cellular tissue, called a _thallus_. They are entirely
destitute of woody fibre. The _Algæ_, _Characeæ_, _Fungi_, and Lichens are
thallogenous plants.
=THEBA′INE.= C_{19}H_{21}NO_{3}. _Syn._ THEBAIA, PARAMORPHIA. A
crystalline substance obtained by Thibourméry from an infusion of opium
that has had its morphia extracted by acting on it by an excess of lime.
=THE′INE.= C_{8}H_{10}N_{4}O_{2}. _Syn._ THEINA. An alkaloid extracted
from tea. It is identical with caffeine, and may be obtained from tea in
the same manner as that substance is from coffee. The best ‘gunpowder tea’
contains fully 6% of theine, about one half of which is lost in the
present careless mode of making infusion of tea for the table.
Mr Lewis Thompson, M.R.C.S., in a contribution to the ‘Medical Times and
Gazette’ for 1871, directs attention to the value of theine as a
therapeutic agent, as well as gives an easy method for its preparation. He
writes as follows:——“I wish to direct the attention of the medical
profession to a valuable agent which has hitherto escaped notice, although
its powers are most unquestionable, and its cost price very trivial. The
article to which I allude is theine, a substance existing in tea and
coffee, and, as I believe, in many other vegetable products.
“As a medicine, theine is powerfully tonic and stimulant, and appears to
possess the tonic virtues of the disulphate of quinia united to the
stimulating power of wine, but with this difference, that the stimulus
from theine is not followed by depression, as in the case of wine and
alcohol.
“Theine seems to act chiefly on the great sympathetic or ganglionic
system of nerves, and but slightly on the brain. I have used it in doses
of from 1 to 5 grams, with very marked advantage, in the low stage of
typhoid fevers, confluent smallpox, and that form of mortification of the
toes which is so singularly fatal to old people. But, in addition to this,
different medical friends of mine have found it useful in hemicrania,
neuralgia, and what has been called relapsing fever; and in the case of an
overdose of opium, it appeared to relieve the narcotic symptoms speedily.
“With regard to the cost of this medicine, I have discovered that in the
ordinary process of roasting coffee, the whole of the theine is driven off
before the torrefaction of the coffee is completed; and thus theine may be
cheaply collected by making the axis of the coffee roaster tubular. If,
instead of a solid axis, we employ at one end of the roasters a tube
passing away to the distance of about three feet, the theine is condensed
in this tube by the refrigerating power of the atmosphere, and may
afterwards be easily dissolved out by a little water, and purified in the
manner about to be indicated.
“As the result of much experience, I have obtained on an average, 75
grains of theine from the roasting of 1 lb. of raw coffee; and when we
reflect that in Great Britain alone, there are more than 13,000 tons of
coffee roasted annually, we see that about 140 tons of theine are wasted
and lost every year by sheer ignorance. It may, perhaps, be thought that
the saving of the theine will damage the flavour of the coffee, but from
experience I know that it has no such effect; and, in point of fact, it is
an advantage to the flavour of the coffee to make both the axes of the
roaster tubular, and to cause a gentle current of air to pass through the
apparatus during the roasting of the coffee, so as to expel the
empyreumatic products that are formed. I will now relate the fact upon
which the purification of theine depends, and when this is once clearly
understood, the manufacture of theine from either tea or coffee becomes an
extremely simple matter. Theine is absolutely insoluble in a concentrated
solution of the carbonate of potash, and thus we may precipitate it from
its admixture with sugar, mucilage, and vegetable extract. If, then, by
means of the subacetate of lead, we have removed from a vegetable infusion
the tannin, malic acid, &c., we have only to evaporate the filtered
solution to a small bulk, and add to it its own weight of dry carbonate of
potash, and the whole of the theine becomes at once insoluble; so that
having collected this insoluble product, and boiled it in rectified
spirits of wine, we have a solution of pure theine, which, after
distilling off the spirit, furnishes crystals fit for immediate use. In
conclusion, I will merely mention a distinctive test for theine,
sufficiently delicate to detect the one thousandth of a grain of that
substance. Dissolve the theine in a small quantity of water, and pass
through this a stream of euchlorine, then allow the fluid to evaporate at
a steam heat; a blood-coloured substance will remain, which, on the
application of a few drops of cold water, forms a beautiful scarlet
solution like red ink. It is, I apprehend, almost unnecessary for me to
say that euchlorine gas is formed by the action of hydrochloric acid upon
the chlorate of potash.
“I ought, perhaps, to add that theine collected as a waste product of
coffee, and purified by myself, has cost me less than threepence per ounce
troy.”