Grains.
{ 17 AMMONIA (pure or gaseous).
{ 43-1/2 Carbonate of ammonia
{ (neutral, hydrated).
{ 59 Sesquicarbonate of ammonia
{ (Ph. L.; translucent, hydrated).
{ 79 Bicarbonate of ammonia
{ (crystallised).
{ 47 POTASSA (anhydrous).
{ 56 Hydrate of potassa (pure
{ caustic potassa).
{ 69 Carbonate of potassa
{ (anhydrous).
{ 83 " " (granulated,
{ commercial).
{ 87 " "
{ (crystallised).
{100 Bicarbonate of potassa
{ (crystallised).
Grains { 31 SODA (anhydrous).
22 Carbonic anhydride } { 40 Hydrate of soda (pure caustic
(dry). } { soda).
63 Oxalic acid } { 53 Carbonate of soda (anhydrous).
(crystallised). } {143 " " (crystallised).
49 Sulphuric acid } are { 84 Bicarbonate of soda
(liquid, }equivalent{ (crystallised).
monohydrated, } to { 83-1/2 Sesquicarbonate of soda
sp. gr. 1·8485). } { (average commercial).
75 Tartaric acid } { 84 Bicarbonate of soda (crystals,
(crystallised). } { or cryst. powder,
1000 Dilute sulphuric acid} { free from moisture).
(sp. gr. 1·033). } { ============
} {
Water--gr. measure. } { 15 LITHIA.
1000 Dilute sulphuric } { 24 Hydrate of lithia.
acid (sp. gr. 1·032). } { 37 Carbonate of lithia.
{ ============
{ 76-1/2 BARYTA (pure, caustic).
{ 85-1/2 Hydrate of baryta.
{ 98-1/2 Carbonate of baryta.
{ 28 LIME (pure, caustic;
{ _i. e._ quick-lime).
{ 37 Hydrate of lime (slaked lime).
{ 50 Carbonate of lime
{ (chalk; marble).
{ 20 MAGNESIA (pure, calcined).
{ 42 Carbonate of magnesia (dry,
{ neutral).
{ 48-1/2 " " (ordinary
{ commercial).
{ 52 STRONIA (pure, caustic).
{ 61 Hydrate of strontia.
{ 74 Carbonate of strontia.
=ALKALOID.= _Syn._ VEGETABLE ALKALI, ORGANIC BASE; ALKALOÏDES (_pl._,
-IDES, or -IDÆ), L.; ALCALOÏDE, ALCALI ORGANIQUE, Fr. In _chemistry_, a
name commonly given to any proximate principle of vegetable origin
possessing alkaline or basic properties, however feeble. In its most
extended sense the term embraces all organic bases, whether obtained from
the animal or vegetable kingdom, or produced artificially. The alkaloids
form a numerous and important class of bodies. They exist in nature nearly
always in the form of salts, the acid being often, like themselves,
peculiar to the plant, or class of plants, in which they are found; whilst
the medicinal activity of the latter, in most cases, almost entirely
depends on their presence.
_Prep._ The following general methods of procuring the alkaloids will be
found applicable to such as full directions are not given for under their
respective heads:--
1. (When the base is insoluble in water, non-volatile, and existing in the
plant in an insoluble form.) The bruised plant is boiled or macerated in
water acidulated with hydrochloric or acetic acid, and the liquor, after
filtration, is neutralised with an alkali (ammonia, potassa, lime, or
magnesia); the resulting precipitate is purified by re-solution in dilute
acid, digestion with a little animal charcoal, and subsequent
crystallisation, or re-precipitation with an alkali; or the first
precipitate is purified by dissolving it once, or, if necessary, several
times, in boiling alcohol, which yields the pure alkaloid either on
cooling or by evaporation.
2. (When the base is insoluble in water, and non-volatile, but existing in
the plant as a soluble salt.) The bruised or sliced plant is boiled or
macerated in water, and the filtered liquor precipitated and otherwise
treated as before.
3. (When the base is soluble in water, and non-volatile.) An infusion made
with very dilute acid, hydrochloric or acetic, is concentrated by a gentle
heat; and the residual liquor treated with potassa (or concentrated
solution of ammonia) and ether conjointly; after repose, the ethereal
solution is decanted and evaporated. For those alkaloids which are
insoluble in ether (as morphia and cinchonia), the previous process may be
adopted.
4. (When the base is both soluble in water and volatile.) The vegetable,
in a bruised or divided state, or its extract, is alkalised with potassa
and distilled; the distillate is neutralised with dilute oxalic or
sulphuric acid, and carefully evaporated to dryness; the residuum is next
digested in alcohol, and the resulting tincture agitated with potassa and
ether, the former being in quantity just sufficient to seize on all the
acid; lastly, the ethereal solution thus formed, on careful evaporation,
leaves the alkaloid nearly pure. It may be further purified by cautious
distillation.
As some of the alkaloids are soluble in excess of the alkaline
precipitant, over-saturation should be carefully avoided; or the
precipitant may be used under the form of carbonate or bicarbonate. When
lime and magnesia are employed, they are boiled for a few minutes with the
solution.
_Props._ Alcoholic or aqueous solutions of the alkaloids generally exhibit
an alkaline reaction with vegetable colours. Like the alkalies, also, they
combine with acids to form salts which, when dissolved in water, are
capable of producing the ordinary phenomena of saline double
decomposition. Their taste is usually intensely bitter.
The majority of the natural alkaloids contain carbon, hydrogen, nitrogen,
and oxygen, and are, at ordinary temperatures, solid, and not volatile
without decomposition. Some natural alkaloids contain carbon, hydrogen,
and nitrogen only; these are, for the most part, liquid at ordinary
temperatures, and can be distilled without decomposition. The greater
number of the artificial alkalies are composed of carbon, hydrogen, and
nitrogen; some, however, contain oxygen in addition. Alkaloids have also
been obtained artificially, in which nitrogen is replaced by phosphorus,
arsenic, antimony, or bismuth. Most of the alkaloids, as they are obtained
in the free state, correspond in function to ammonia, NH_{3}, rather than
to the fixed alkalies; that is to say, they form salts by direct union
with acids, without elimination of water or any other substance. In order
to make them strictly comparable to the fixed alkalies, they require, like
ammonia, the addition of water (H_{2}O) to their formulæ; they may then be
considered as hydrates of compound radicles analogous to ammonium.
_Physiological action._ The alkaloids generally possess great medicinal
power; some of them act with terrific energy, and are the most violent
poisons with which we are acquainted. Perfectly pure aconitia is about 200
times more poisonous than arsenic, and at least 50 times more poisonous
than ordinary medicinal prussic acid. The greater number act on animals in
the same way as the plants which produce them, provided they are given in
proportionately small doses. Many of them, when judiciously administered,
are most valuable medicines.
_Pois., Ant., &c._ Some of the alkaloids act as narcotic or stupefying
poisons; others are classed with the narcotico-acrid poisons, or those
which produce both narcotism and irritation of the parts they touch. The
general symptoms produced by opium and its preparations may be taken as an
example of the former; those from aconite and strychnia, of the latter. In
large doses of the greater number, narcotism predominates; in smaller
ones, irritation; they are rarely coexistent.--_Treatm._ No common
antidote to the effects of this class of substances has yet been
discovered. The only safe treatment, of at all general application, is to
immediately clear the stomach by means of a strong and quick-acting emetic
(as sulphate of zinc), or the stomach-pump, and to administer copious and
continued draughts of astringent vegetable solutions (as of tannin,
nut-galls, oak-bark, or what is always at hand--very strong tea or
coffee). These may be followed by or combined with a smart purge of castor
oil, as soon as the stomach is thoroughly cleared of the poison. M.
Bouchardat strongly recommends a solution of iodine, 3 gr., and iodide of
potassium, 6 gr., in pure water, 16 fl. oz., in cases of poisoning by
OPIUM, ACONITE, COLCHICUM, DEADLY NIGHTSHADE, HEMLOCK, NUX VOMICA, &c., or
by the alkaloids obtained from them--ACONITINE, ATROPIA, COLCHICINA,
CONIA, MORPHIA, STRYCHNIA, &c., or their salts; but _not_ where foxglove
or digitalin has been taken. The stomach having been well emptied by an
emetic, the solution is to be given by wine-glassfuls for some time; the
vomiting being still encouraged during the early part of the
administration of the antidote. In the case of narcotics (as opium,
morphia, &c.), this is to be followed by the free use of a strong infusion
of coffee. According to Dr Garrod, purified animal charcoal is an
'excellent antidote' to many of the alkaloids, including those above
enumerated, when taken in poisonous doses; as it not merely absorbs them,
but, for the most part, renders them inert. To be serviceable it should be
recently prepared and fresh-burnt; and should be given in doses of about
an ounce at a time, diffused in warm or tepid water, and frequently
repeated. The vomiting which follows its use, owing to the warm water,
proves advantageous; but after a sufficient time may be lessened by
employing less water, or cooler or even cold water. Drowsiness, if
present, may be combated by the subsequent use of strong coffee or tea, as
before. We have seen this plan succeed in several cases.--_Lesions._
These, like the symptoms, vary. In some cases there are redness and
inflammation of the stomach and intestines, and turgescence of the vessels
of the lungs and brain; in others, these appearances are either slight or
wholly wanting. Wherever there has been much cerebral disturbance, traces
of congestion are usually discernible.
_Detec., Tests, &c._ The identification of the pure alkaloids is extremely
simple; but their detection, when combined with organic and colouring
matters, is a task of considerable difficulty. One or other of the
following plans may be adopted for this purpose:--
1. (Merck.) The matter under examination is digested, for several hours,
with concentrated acetic acid, added in sufficient quantity to produce a
strongly acid reaction; the fluid portion is then strained from the
insoluble matter, and the latter being washed with water acidulated with
acetic acid, the mixed liquors are gently evaporated to dryness in a water
bath; the residuum of the evaporation is boiled first with rectified
spirit, and next with rectified spirit acidulated with acetic acid; the
mixed liquors are again evaporated, the residuum redissolved or diluted
with distilled water, and carbonate of soda or potassa added to feebly
alkaline reaction, and the whole, after evaporation to the consistence of
a syrup, set aside to repose for 24 hours; it is now again diluted with
water, filtered, and the insoluble portion washed with cold distilled
water, and digested with concentrated acetic acid; this last solution is
diluted with distilled water, and decoloured with pure blood-charcoal (if
it be necessary); the fluid, either at once, or after cautious
evaporation, may then be tested for the alkaloids, in the usual manner.
The charcoal previously used should also be tested in the way described
below. This method answers admirably with all the NON-VOLATILE ALKALOIDS,
and may be applied to the stomach and viscera, and their contents, and to
food, &c., in cases of poisoning.
2. (Stas.) The suspected matter, in a finely divided state, is digested,
at 160° to 165° Fahr., with twice or thrice its weight of strong alcohol
acidulated (according to the quantity) with 1/2 dr. to 2 or 3 dr., or
more, of pure oxalic or tartaric acid. After a sufficient time, and when
the whole has become quite cold, it is thrown on a filter, and the
undissolved portion, after being squeezed dry, is washed with strong
alcohol. The mixed and filtered alcoholic liquids are then evaporated at a
temperature not exceeding 95° Fahr., and, if no insoluble matter
separates, the evaporation is continued nearly to dryness;[19] but if
fatty or other insoluble matter separates during the process of
concentration, the concentrated fluid is passed through a moistened
filter, and the filtrate evaporated nearly to dryness, as before. The
residuum is next digested with absolute alcohol, in the cold, the
insoluble portion, after filtration, washed with alcohol, and the mixed
filtrates again evaporated in the air, or in vacuo. The acid residue is
now dissolved in a little distilled water, and bicarbonate of soda added
as long as effervescence ensues. To this mixture 4 or 5 times its volume
of ether is added, and after lengthened agitation (the bottle or tube
being held in a cold wet cloth), the whole is allowed to repose for a
short time. A little of the supernatant ether is now removed to a small
glass capsule or watch-glass, and allowed to evaporate spontaneously.[19]
When this leaves oily streaks upon the glass, which gradually collect into
a small drop, which emits, when gently heated, a disagreeable, pungent,
and stifling odour, the presence of a LIQUID VOLATILE BASE or ALKALOID is
inferred; whilst a solid residue or a turbid fluid with small solid
particles floating in it, indicates a NON-VOLATILE SOLID BASE.[20] In
either case the blue colour of reddened litmus is permanently restored by
the residuum. If no residuum is left on the capsule, some solution of pure
soda or potassa is added to the liquid, the whole well agitated for
several minutes, and the ether (after repose) decanted; an operation which
is repeated with fresh ether a second, third, and even a fourth time. The
base, or bases (if any are present), will now be found in the mixed
ethereal solution, which is, therefore, tested as before. The presence of
an alkaloid being detected, the mixed ethereal solutions are allowed to
evaporate spontaneously, care being taken, if a volatile alkaloid be
present, to neutralise the liquid with an acid before the final
evaporation. The last residuum is then tested for the particular alkaloid
present, as before.[21]
[Footnote 19: The evaporation, according to Stas, should be conducted
under a bell-glass over sulphuric acid, with or without rarefaction of the
air; or in a tubular retort through which a current of air is made to
pass.]
[Footnote 20: A merely disagreeable animal odour, without pungency, is
here disregarded.]
[Footnote 21: 'Bulletin de l'Académie de Méd. Belgique,' ix, 304; 'Jahrb.
f. prakt. Pharm,' xxiv, 313; &c.]
This method, according to Stas, answers well for all the ALKALOIDS which
are soluble in ether; including--ACONITIA, ANILINE, ATROPIA, BRUCIA,
CODEIA, COLCHICINA, CONIA, DELPHIA, EMETINA, HYOSCYAMINE, MORPHIA (?),
NICOTIA, PETININE, PICOLINE, SOLANINE, STRYCHNIA, VERATRIA, &c. By means
of it Stas found nicotia in the heart-blood of a poisoned dog. With such
alkaloids as are, however, only very sparingly soluble in ether (as
morphia for instance), the result must, necessarily, be doubtful. To
detect these, as well as all the alkaloids which are insoluble in ether,
it is, therefore, necessary, as directed by Otto, to add to the alkaline
fluid left by the decantation of the ether, sufficient solution of soda to
dissolve the morphia, &c. (if any has separated), and after the expulsion
of the last traces of the ether by a gentle heat, to add a concentrated
solution of hydrochlorate of ammonia, and to allow the mixture to repose
for some time in the open air. When MORPHIA is present, it separates under
the form of small crystals.[22] Or the alkaline liquor may be diluted with
distilled water, and treated with charcoal, and this with alcohol, in the
manner noticed under method 4 (_below_).
[Footnote 22: Otto's 'How to Detect Poisons.']
4. (Graham and Hoffmann--slightly modified.) 2 or 3 oz. of purified animal
charcoal are digested in about 1/2 gal. of the (neutral or only slightly
acid) aqueous fluid under examination, with frequent agitation, for 10 to
12 hours, or longer. The liquid is then filtered, and the charcoal left on
the filter is washed twice with cold distilled water. The charcoal
is then boiled for 1/2 an hour with about 1/2 a pint of rectified spirit
of 80 or 90%; the ebullition being conducted in a flask having a very long
tube, open at both ends, fitted air-tight through the cork, to prevent
loss of the alcohol by evaporation. The spirit, which now contains the
alkaloid (if any was present in the original liquor), is next filtered
whilst hot, and the filtrate is submitted to distillation until the whole
of the alcohol is removed. A small quantity (commonly a few drops) of
solutions of potassa is then added to the residual aqueous liquor,
followed by 1 to 2 fl. oz. of pure ether, after which the whole is well
agitated for several minutes, and allowed to repose for a short time.
Lastly, the supernatant ether is decanted, and allowed to evaporate
spontaneously, when the residuum (if any) left in the capsule may be
tested by reagents, as before.
This method was devised for the detection of STRYCHNIA and NUX VOMICA in
malt-liquors; but it is equally applicable to the detection of ANY
ALKALOID which is soluble in ether. The CHARCOAL TEST may also be employed
to detect alkaloids which are insoluble in ether; but then the base must
be sought in the aqueous residuum obtained by the evaporation of the
alcohol.[23]
[Footnote 23: 'Journ. of the Chem. Soc.,' v, 173.]
The presence of the alkaloids and their salts, in clear solutions, may be
thus determined:--
I. (Fresenius).--1. The solution is rendered very slightly alkaline with
dilute solution of potassa or soda, added drop by drop:--
a. No precipitate is formed; total absence of the alkaloids.
(See 4, _below_.)
b. A precipitate is formed:--solution of potassa or soda is
added, drop by drop, until the liquid exhibits a strong
alkaline reaction:--
[Greek: a]. The precipitate redissolves; absence of Brucia,
Cinchonia, Narcotina, Quina, Strychnia, and Veratria; probable
presence of MORPHIA.
[Greek: b]. Precipitate does not redissolve, or not completely;
probable presence of one or more of the first six of the
above-named alkaloids:--the fluid is filtered from the
precipitate, mixed with either bicarbonate of soda or of
potassa, gently boiled nearly to dryness, and treated with
water. If it dissolves completely; absence of morphia; an
insoluble residue indicates MORPHIA.
2. The precipitate 1. _b._ [Greek: b]. is washed with cold distilled
water, dissolved in a slight excess of dilute sulphuric acid, neutralised
with a saturated solution of bicarbonate of soda, and allowed to repose a
few hours:[24]--
[Footnote 24: Before setting the glass aside the liquor should be well
mixed, and the glass stirrer vigorously rubbed against the sides of the
vessel.]
_a_. No precipitate; absence of Cinchonia, Narcotina, and
Quina:--the solution is gently evaporated nearly to dryness,
and treated with cold water:--if it dissolves completely,
pass on to 4; if there is an insoluble residue, it may
contain Brucia, Strychnia, or Veratria. (See 3.)
_b._ A precipitate:--the filtered fluid is treated as directed
at 2 _a_.; the precipitate is washed with cold distilled
water, dissolved in a little hydrochloric acid, ammonia is
added in excess, and subsequently a sufficient quantity of
ether, agitation being had recourse to:--
[Greek: a]. The precipitate formed by the ammonia redissolves
completely in the ether, and the clear fluid separates
into two layers; absence of Cinchonia; probable presence
of QUINA or NARCOTINA.
[Greek: b]. The precipitate produced by the ammonia does not
redissolve in the ether, or not completely; probable presence of
CINCHONIA, and perhaps also of Quina or Narcotina. The
filtered liquid may be tested for these alkaloids as at
_a_.
3. The insoluble residuum after the evaporation of the solution 2. _a._,
or of the filtrate 2. _b._, is now dried in a water bath, and digested
with absolute alcohol:--
_a._ It dissolves completely; absence of strychnia; probable
presence of BRUCIA, QUINA (?), or VERATRIA:--the alcoholic
solution is evaporated to dryness, and, if quina has been
already detected, the residue is divided into two portions,
one of which is tested for Brucia, the other for Veratria.
_b._ It does not dissolve, or not completely; probable presence
of STRYCHNIA, and perhaps also of Brucia and Veratria:--the
filtered fluid is divided into two portions, and tested
separately as at _a_.
4. The original liquid 1. _a_. may contain Salicine, a proximate vegetable
principle closely allied to the alkaloids:--a portion is boiled with
hydrochloric acid for some time; the formation of a precipitate shows the
presence of SALICIN. (See 2, _below_.)[25]
[Footnote 25: For further information on this subject, see the admirable
'System of Qual. Chem. Anal.,' by Dr C. R. Fresenius. Churchill.]
II. (Larocque and Thibierge.) Terchloride of gold is recommended, by these
writers, as a more decisive test for the alkaloids than the 'double
chloride of gold and sodium' commonly employed for this purpose. The
following are the colours of the precipitates which it produces with the
aqueous solution of their salts:--BRUCIA, milk-brown, passing into
coffee-brown, and lastly chocolate-brown:--CINCHONIA, sulphur
yellow:--MORPHIA, yellow, then bluish, and lastly violet; in this last
state the gold is reduced, and the precipitate is insoluble in water,
alcohol, the caustic alkalies, and sulphuric, nitric, and hydrochloric
acid; it forms with aqua regia a solution which is precipitated by
protosulphate of iron:--QUINA, buff-coloured:--STRYCHNIA,
canary-yellow:--VERATRIA, pale greenish-yellow. All these precipitates,
with the exception mentioned, are very soluble in alcohol, insoluble in
ether, and only slightly soluble in water. Those with morphia and brucia
are sufficiently marked to prevent these alkalies from being mistaken for
each other; and those with brucia and strychnia are, in like manner,
easily distinguishable.
III.--Mr Wanklyn discriminates the different alkaloids from the estimation
of the ammonia they evolve. His process is as follows:--A small flask with
a lateral tube, and connected with a Liebig's condenser, is charged with
about 25 c. c. of an alkaline solution of permanganate potash made by
dissolving 200 grammes of caustic potash and 8 grammes of crystallised
permanganate of potash in 1 litre of water. A minute quantity of the
alkaloid carefully and accurately weighed is now introduced, and the
mixture slowly distilled. The most satisfactory results are obtained by
treating from 1 to 5 milligrammes of the alkaloid in this way, but
quantities so small as 1/10th of a milligram will in skilled hands give
accurate results. The ammonia is formed in the distillate by Nesslerising
it, as described under WATER ANALYSIS. For all practical purposes the
poisonous alkaloids may be divided into four classes:
(a) Those which yield from 5 to 2 per cent. of ammonia.
(b) Those which yield from 2 to 3 per cent. of ammonia.
(c) Those which yield from 3 to 5 per cent. of ammonia.
(d) Those which yield a larger quantity than 5 per cent., _e.g._