ACIDS. A class of chemical substances characterised by the property of
combining with and neutralising the alkaline and other bases, and of
thereby forming a peculiar class of bodies called salts. The acids which
constitute objects of special manufacture for commercial purposes are
the following:--acetic, arsenious, carbonic, chromic, citric, malic,
muriatic, nitric, oxalic, phosphoric, sulphuric, tartaric, which see.
ACROSPIRE. (_Plumule_, Fr.; _Blattkeim_, Germ.) That part of a
germinating seed which botanists call the plumula, or plumes. See BEER
and MALT.
ADDITIONS. Such articles as are added to the fermenting wash of the
distiller are distinguished by this trivial name.
ADIPOCIRE. Fr. (_Fettwachs_, Germ.) The fatty matter generated in dead
bodies buried under peculiar circumstances. In 1786 and 1787, when the
churchyard of the _Innocents_, at Paris, was cleaned out, and the bones
transported to the catacombs, it was discovered that not a few of the
_cadavres_ were converted into a saponaceous white substance, more
especially many of those which had been interred for fifteen years in
one pit, to the amount of 1500, in coffins closely packed together.
These bodies were flattened, in consequence of their mutual pressure;
and, though they generally retained their shape, there was deposited
round the bones of several a grayish white, somewhat soft, flexible
substance. Fourcroy presented to the Academy of Sciences, in 1789, a
comprehensive memoir upon this phenomenon, which appeared to prove that
the fatty body was an ammoniacal soap, containing phosphate of lime;
that the fat was similar to spermaceti, as it assumed on slow cooling a
foliated crystalline structure; as also to wax, as, when rapidly cooled,
it became granular: hence he called it _Adipocire_. Its melting point
was 52·5° C. (126·5° Fahr.). He likewise compared this soap to the fat
of gall-stones, and supposed it to be a natural product of the slow
decomposition of all animal matter, except bones, nails, and hairs.
This substance was again examined by Chevreul in 1812, and was found by
him to contain margaric acid, oleic acid, combined with a yellow
colouring, odorous matter, besides ammonia, a little lime, potash, oxide
of iron, salts of lactic acid, an azotized substance; and was therefore
considered as a combination of margaric and oleic acids, in variable
proportions (whence arose its variable fusibility), but that it was not
analogous with either spermaceti or cholesterine (gallstones). These fat
acids are obviously generated by the reaction of the ammonia upon the
margarine and oleine, though they eventually lose the greater part of
that volatile alkali.
According to the views of both Gay Lussac and Chevreul, this _adipocire_
proceeds solely from the pre-existing fat of the dead body, and not from
the flesh, tendons, or cartilages, as had been previously imagined;
which had led to some expensive and abortive attempts, upon the great
scale of manufacture, to convert the dead bodies of cattle into
adipocire, for the purposes of the candle-maker or soap-boiler, by
exposing them for some time to the action of moisture.
Von Hartkol made experiments during 25 years upon this subject, from
which he inferred, that there is no formation of adipocire in bodies
buried in dry ground; that in moist earth the fat of the dead body does
not increase, but changes into a fetid saponaceous substance, incapable
of being worked into either soap or candles; that the dead bodies of
_mammalia_ immersed in running water, leave behind after 3 years a pure
fat, which is more abundant from young than from old animals; that the
intestines afford more fat than the muscles; that from this fat, without
any purification, candles may be made, as void of smell, as hard, and as
white, as from bleached wax; that from cadavers immersed for 3 years in
stagnant water, more fat is procured than from those in running water,
but that it needs to be purified before it can be made into soap or
candles.
The cause of the difference between Hartkol’s and Chevreul’s results
cannot be assigned, as the latter has not published his promised remarks
upon the subject. At any rate, dead animal matter can be worked up more
profitably than in making artificial _adipocire_.
ADIT. The horizontal entrance of a mine. It is sometimes called the
drift. See MINING and METALLURGY.
ADULTERATION. The debasing any product of manufacture, especially
chemical, by the introduction of cheap materials. The art of
ascertaining the genuineness of the several products will be taught
under the specific objects of manufacture.
ÆTHER. See ETHER.
AFFINITY. The chemical term denoting the peculiar attractive force which
produces the combination of dissimilar substances; such as of an alkali
with an acid, or of sulphur with a metal.
AGARIC. A species of boletus or fungus, which grows in dunghills; with
the salts of iron it affords a black dye. It is said to be convertible
into a kind of china ink.
AGATE. A siliceous mineral which is cut into seals and other forms for
the coarser kinds of jewellery. See GEM.
AIR. See VENTILATION.
ALABASTER, is a stone usually white, and soft enough to be scratched by
iron. There are two kinds of it: the gypseous, which is merely a natural
semi-crystalline sulphate of lime; and the calcareous alabaster, which
is a carbonate of lime. The oriental alabaster is always of the latter
kind, and is most esteemed, because it is agreeably variegated with
lively colours, and especially with zones of honey-yellow, yellow-brown,
red, &c.; it is, moreover, susceptible of taking a marble polish.
The fineness of the grain of alabaster, the uniformity of its texture,
the beauty of its polished surface, and its semi-transparency, are the
qualities which render it valuable to the sculptor and to the
manufacturer of ornamental toys.
The limestone alabaster is frequently found as a yellowish-white deposit
in certain fountains. The most celebrated spring of this kind is that of
the baths of San Filippo, in Tuscany. The water, almost boiling hot,
runs over an enormous mass of stalactites, which it has formed, and
holds the carbonate of lime in solution by means of sulphuretted
hydrogen (according to M. Alexandre Brongniart), which escapes by
contact of the atmosphere. Advantage has been taken of this property to
make _basso relievos_ of considerable hardness, by placing moulds of
sulphur very obliquely, or almost upright, in wooden tubs open at the
bottom. These tubs are surmounted at the top with a large wooden cross.
The water of the spring, after having deposited in an external conduit
or cistern the coarser sediment, is made to flow upon this wooden cross,
where it is scattered into little streamlets, and thence lets fall, upon
the sulphur casts, a precipitate so much the finer the more nearly
vertical the mould. From one to four months are required for this
operation, according to the thickness of the deposited crust. By
analogous processes, the artists have succeeded in moulding vases,
figures of animals, and other objects, in relief, of every different
form, which require only to be trimmed a little, and afterwards
polished.
The common alabaster is composed of sulphuric acid and lime, though some
kinds of it effervesce with acids, and therefore contain some carbonate
of lime. This alabaster occurs in many different colours, and of very
different degrees of hardness, but it is always softer than marble. It
forms, usually, the lowest beds of the gypsum quarries. The sculptors
prefer the hardest, the whitest, and those of a granular texture, like
Carrara marble, and so like that they can only be distinguished by the
hardness.
The alabaster is worked with the same tools as marble; and as it is many
degrees softer, it is so much the more easily cut; but it is more
difficult to polish, from its little solidity. After it has been
fashioned into the desired form, and smoothed down with pumice stone, it
is polished with a pap-like mixture of chalk, soap, and milk; and, last
of all, finished by friction with flannel. It is apt to acquire a
yellowish tinge.
Besides the harder kinds, employed for the sculpture of large figures,
there is a softer alabaster, pure white and semi-transparent, from which
small ornamental objects are made, such as boxes, vases, lamps, stands
of time-pieces, &c. This branch of business is much prosecuted in
Florence, Leghorn, Milan, &c., and employs a great many turning lathes.
Of all the alabasters the Florentine merits the preference, on account
of its beauty and uniformity, so that it may be fashioned into figures
of considerable size; for which purpose there are large work-shops where
it is cut with steel saws into blocks and masses of various shapes.
Other sorts of gypsum, such as that of Salzburg and Austria, contain
sand veins, and hard nodules, and require to be quarried by cleaving and
blasting operations, which are apt to crack it, and unfit it for all
delicate objects of sculpture. It is, besides, of a gray shade, and
often stained with darker colours.
The alabaster best adapted for the fine arts is pretty white when newly
broken, and becomes whiter on the surface by drying. It may be easily
cut with the knife or chisel, and formed into many pleasing shapes by
suitable steel tools. It is worked either by the hand alone, or with the
aid of a turning lathe. The turning tools should not be too thin or
sharp-edged; but such as are employed for ivory and brass are most
suitable for alabaster, and are chiefly used to shave and to scratch the
surface. The objects which cannot be turned may be fashioned by the
rasping tools, or with minute files, such as variegated foliage. Fine
chisels and graving tools are also used for the better pieces of
statuary.
For polishing such works, a peculiar process is required: pumice stone,
in fine powder, serves to smooth down the surfaces very well, but it
soils the whiteness of the alabaster. To take away the unevennesses and
roughnesses dried shave-grass (_equisetum_) answers best. Frictions with
this plant and water polish down the asperities left by the chisel: the
fine streaks left by the grass may be removed by rubbing the pieces with
slaked lime, finely pulverised and sifted, made into a paste, or putty,
with water. The polish and satin-lustre of the surface are communicated
by friction, first with soap-water and lime, and finally with powdered
and elutriated talc or French chalk.
Such articles as consist of several pieces are joined by a cement
composed of quicklime and white of egg, or of well-calcined and
well-sifted Paris plaster, mixed with the least possible quantity of
water.
Alabaster objects are liable to become yellow by keeping, and are
especially injured by smoke, dust, &c. They may be in some measure
restored by washing with soap and water, then with clear water, and
again polished with shave-grass. Grease spots may be removed either by
rubbing with talc powder, or with oil of turpentine.
The surface of alabaster may be etched by covering over the parts that
are not to be touched with a solution of wax in oil of turpentine,
thickened with white lead, and immersing the articles in pure water
after the varnish has set. The action of the water is continued from 20
to 50 hours, more or less, according to the depth to which the etching
is to be cut. After removing the varnish with oil of turpentine, the
etched places, which are necessarily deprived of their polish, should be
rubbed with a brush dipped in finely-powdered gypsum, which gives a kind
of opacity, contrasting well with the rest of the surface.
Alabaster may be stained either with metallic solutions, with spirituous
tinctures of dyeing plants, or with coloured oils, in the same way as
marbles.
This substance has been hardened, it is said, by exposing it to the heat
of a baker’s oven for 10 or 20 hours, after taking it out of the quarry,
and giving it the figure, roughly, which it is intended to have. After
this exposure, it must be dipped for two minutes in running water; when
it is cold, it must be dipped a second time for the same period. On
being exposed to the air for a few days, alabaster so treated acquires a
marble-like hardness. I doubt the truth of this statement.
ALBUM GRÆCUM. The white dung of dogs, sometimes used to soften leather
in the process of dressing it after the depilatory action of lime.
ALCARAZZAS. A species of porous earthenware, made in Spain, for cooling
liquors. See POTTERY.
ALCOHOL. The well-known intoxicating liquor procured by distillation
from various vegetable juices, and infusions of a saccharine nature,
which have undergone the vinous fermentation. Common alcohol, or proof
spirit, as it is called, contains about one half its weight of water. It
may be concentrated till its specific gravity becomes so low as 0·825,
by simple redistillation at a steam or water-bath heat; but to make it
stronger, we must mix with it, in the still or retort, dry carbonate of
potash, muriate of lime, or some other substances strongly attractive of
water, and then it may be obtained of a specific gravity so low as 0·791
at 16° Reaumur (68° Fahr.), water being 1·000. At 0·825, it contains,
still, 11 per cent. of water; and in this state it is as volatile as
absolute alcohol, on account of the inferior density of the aqueous
vapour, compared to the alcoholic. Indeed, according to Yelin and Fuchs,
the boiling point of anhydrous alcohol is higher than of that which
contains 2 or 3 per cent. of water; hence, in the distillation of
alcohol of 94 per cent., the first portions that come over are more
aqueous than the following. Absolute alcohol has its boiling point at
168-1/2° Fahr.: but when it holds more than 6 per cent. of water, the
first portions that come over are richest in alcohol, and the
temperature of the boiling point, or of the spirituous vapour, is always
higher the longer the distillation continues. According to Gröning’s
researches, the following temperatures of the alcoholic vapours
correspond to the accompanying contents of alcohol in per centage of
volume, which are disengaged in the boiling of the spirituous liquid.
+------------+-----------+-----------+
| |Alcoholic |Alcoholic |
|Temperature.|content of |content of |
| |the vapour.|the boiling|
| | |liquid. |
+------------+-----------+-----------+
|Fahr. 170·0 | 93 | 92 |
| 171·8 | 92 | 90 |
| 172 | 91 | 85 |
| 172·8 | 90-1/2 | 80 |
| 174 | 90 | 70 |
| 174·6 | 89 | 70 |
| 176 | 87 | 65 |
| 178·3 | 85 | 50 |
| 180·8 | 82 | 40 |
| 183 | 80 | 35 |
| 185 | 78 | 30 |
| 187·4 | 76 | 25 |
| 189·8 | 71 | 20 |
| 192·0 | 68 | 18 |
| 164 | 66 | 15 |
| 196·4 | 61 | 12 |
| 198·6 | 55 | 10 |
| 201 | 50 | 7 |
| 203 | 42 | 5 |
| 205·4 | 36 | 3 |
| 207·7 | 28 | 2 |
| 210 | 13 | 1 |
| 212 | 0 | 0 |
+------------+-----------+-----------+
Gröning undertook this investigation in order to employ the thermometer
as an alcoholmeter in the distillation of spirits; for which purpose he
thrust the bulb of the thermometer through a cork, inserted into a tube
fixed in the capital of the still. The state of the barometer ought also
to be considered in making comparative experiments of this kind. Since,
by this method, the alcoholic content may be compared with the
temperature of the vapour that passes over at any time, so, also, the
contents of the whole distillation may be found approximately; and the
method serves as a convenient means of making continual observations on
the progress of the distillation.
The temperature, corresponding to a certain per centage of alcohol in
vapour, suggests the employment of a convenient method for obtaining, at
one process, a spirit as free from water as it can be made by mere
distillation. We place over the top of the capital a water-bath, and
lead up through it a spiral pipe from the still, which there passes
obliquely downwards, and proceeds to the refrigeratory. If this bath be
maintained, by a constant influx of cold water, at a certain
temperature, only the alcoholic vapour corresponding to that temperature
will pass over, and the rest will be recondensed and returned into the
still. If we keep the temperature of the water at 174°, for example, the
spirituous vapour which passes over will contain 90 per cent. of
absolute alcohol, according to the preceding table. The skilful use of
this principle constitutes the main improvement in modern distilleries.
See DISTILLATION and STILL.
Another method for concentrating alcohol is that discovered by
Sömmering, founded upon the property of ox bladders to allow water to
pass through and evaporate out of them, but not to permit alcohol to
transpire, or only in a slight degree. Hence, if an ox’s bladder is
filled with spirit of wine, well tied at the mouth, and suspended in a
warm place, the water will continually exhale, and the alcohol will
become nearly anhydrous; for in this way alcohol of 97 or 98 per cent.
may be obtained.
According to Sömmering, we should take for this purpose the bladder of
an ox or a calf, soak it for some time in water, then inflate it and
free it from the fat and the attached vessels; which is to be also done
to the other surface, by turning it inside out. After it is again
inflated and dried, we must smear over the outer side twice, and the
inner side four times, with a solution of isinglass, by which its
texture is made closer, and the concentration of the alcohol goes on
better. A bladder so prepared may serve more than a hundred times. It
must be charged with the spirits to be concentrated, leaving a small
space vacant, it is then to be tightly bound at the mouth, and suspended
in a warm situation, at a temperature of 122° Fahr., over a sand-bath,
or in the neighbourhood of an oven. The surface of the bladder remains
moist with the water, as long as the sp. gr. of the contained spirit is
greater than 0·952. Weak spirit loses its water quicker than strong; but
in from 6 to 12 hours the alcohol may be concentrated, when a suitable
heat is employed. This economical method is particularly applicable in
obtaining alcohol for the preparation of varnishes. When the alcohol is
to serve for other purposes, it must be freed, by distillation, from
certain matters dissolved out of the bladder. Alcohol may likewise be
strengthened, as Sömmering has ascertained when the vessel that contains
the spirit is bound over with a bladder which does not come into contact
with the liquid. Thus, too, all other liquors containing alcohol and
water, as wine, cider, &c., may be made more spirituous.
To procure absolute alcohol, we must take chloride of calcium recently
fused, reduce it to coarse powder, and mix it with its own weight of
spirit of wine, of sp. gr. 0·833, in a bottle, which is to be well
stoppered, and to be agitated till the salt is dissolved. The clear
solution is to be poured into a retort, and half of the volume of the
alcohol employed, or so much as has the sp. gr. 0·791 at 68° Fahr., is
to be distilled off at a gentle heat. Quicklime has also been employed
for the same purpose, but it is less powerful and convenient. Alcohol,
nearly free from water, may be obtained without distillation, by adding
dry carbonate of potash to a spirit of wine, of sp. gr. 0·825. The water
combines with the potash, and falls to the bottom in a dense liquid,
while the pure spirit floats on the surface. This contains however a
little alkali, which can only be separated by distillation.
Anhydrous alcohol is composed by weight of 52·66 carbon, 12·90 hydrogen,
and 34·44 of oxygen. It has a very powerful attraction for water, and
absorbs it from the atmosphere; therefore it must be kept in well-closed
vessels. It also robs vegetable and animal bodies of their moisture; and
hence common alcohol is employed for preserving anatomical preparations.
Alcohol is a solvent for many substances: resins, essential oils,
camphor, are abundantly dissolved by it, forming varnishes, perfumed
spirits, &c. The solution of a resin or essential oil in alcohol becomes
milky on the addition of water, which, by its attraction for alcohol,
separates these substances. Several salts, especially the deliquescent,
are dissolved by it, and some of them give a colour to its flame; thus,
the solutions of the salts of strontia in alcohol burn with a crimson
flame, those of copper and borax green, lime reddish, and baryta yellow.
When water is mixed with alcohol, heat and a condensation of volume are
the result; these effects being greatest with 54 per cent. of alcohol
and 46 of water, and thence decreasing with a greater proportion of
water. For alcohol which contains 90 per cent. of water, this
condensation amounts to 1·94 per cent. of the volume; for 80 per cent.,
2·87; for 70 per cent., 3·44; for 60 per cent., 3·73; for 40 per cent.,
3·44; for 30 per cent., 2·72; for 20 per cent., 1·72; for 10 per cent.,
0·72. Hence, to estimate the quantity of alcohol in any spirit it is
necessary that the specific gravity be ascertained for each determinate
proportion of alcohol and water that are mixed together. When this is
done, we may, by means of an areometer constructed for liquids lighter
than water, determine the strength of the spirit, either by a scale of
specific gravities or by an arbitrary graduation corresponding to
certain commercial objects, and thus we may determine the per centage of
alcohol in whisky or brandy of any strength or purity. An areometer
intended for this use has been called an alcoholmeter, in particular
when the scale of it is so graduated that, instead of the specific
gravity, it indicates immediately the per centage of anhydrous alcohol
in a given weight or volume of the liquid. The scale graduated according
to the per centage of pure alcohol by weight, constitutes the
alcoholmeter of Richter; and that by the per centage in volume, the
alcoholmeter of Tralles and Gay Lussac.
As liquors are sold in general by the measure, not by the weight, it is
convenient, therefore, to know the alcoholic content of the mixtures in
the per centage by volume. Tralles has constructed new tables upon the
principles of those of Gilpin, in which the proportion is given by
volume, and anhydrous alcohol is assumed for the basis; which, at 60°
Fahr., has a specific gravity of 0·7939 compared with water at its
maximum density, or a specific gravity 0·7946 compared with water of the
temperature of 60° Fahr. Gilpin’s alcohol of 0·825 contains 92·6 per
cent. by volume of anhydrous alcohol.
The following table exhibits the per centage of anhydrous alcohol by
volume, at a temperature of 60° Fahr., in correspondence with the
specific gravities of the spirits, water being considered at 60° Fahr.
to have a specific gravity of 0·9991.
Alcoholmetrical Table of Tralles.
+------------+------------+----------+
|Alcohol in | Specific |Difference|
|100 measures| gravity | of the |
| of spirit. |at 60° Fahr.| sp. gr. |
+------------+------------+----------+
| 0 | 9991 | |
| 1 | 9976 | 15 |
| 2 | 9961 | 15 |
| 3 | 9947 | 14 |
| 4 | 9933 | 14 |
| 5 | 9919 | 14 |
| 6 | 9906 | 13 |
| 7 | 9893 | 13 |
| 8 | 9881 | 12 |
| 9 | 9869 | 12 |
| 10 | 9857 | 12 |
| 11 | 9845 | 12 |
| 12 | 9834 | 11 |
| 13 | 9823 | 11 |
| 14 | 9812 | 11 |
| 15 | 9802 | 10 |
| 16 | 9791 | 11 |
| 17 | 9781 | 10 |
| 18 | 9771 | 10 |
| 19 | 9761 | 10 |
| 20 | 9751 | 10 |
| 21 | 9741 | 10 |
| 22 | 9731 | 10 |
| 23 | 9720 | 11 |
| 24 | 9710 | 10 |
| 25 | 9700 | 10 |
| 26 | 9689 | 11 |
| 27 | 9679 | 10 |
| 28 | 9668 | 11 |
| 29 | 9657 | 11 |
| 30 | 9646 | 11 |
| 31 | 9634 | 12 |
| 32 | 9622 | 12 |
| 33 | 9609 | 13 |
| 34 | 9596 | 13 |
| 35 | 9583 | 13 |
| 36 | 9570 | 13 |
| 37 | 9556 | 14 |
| 38 | 9541 | 15 |
| 39 | 9526 | 15 |
| 40 | 9510 | 16 |
| 41 | 9494 | 16 |
| 42 | 9478 | 16 |
| 43 | 9461 | 17 |
| 44 | 9444 | 17 |
| 45 | 9427 | 17 |
| 46 | 9409 | 18 |
| 47 | 9391 | 18 |
| 48 | 9373 | 18 |
| 49 | 9354 | 19 |
| 50 | 9335 | 19 |
| 51 | 9315 | 20 |
| 52 | 9295 | 20 |
| 53 | 9275 | 20 |
| 54 | 9254 | 21 |
| 55 | 9234 | 20 |
| 56 | 9213 | 21 |
| 57 | 9192 | 21 |
| 58 | 9170 | 22 |
| 59 | 9148 | 22 |
| 60 | 9126 | 22 |
| 61 | 9104 | 22 |
| 62 | 9082 | 22 |
| 63 | 9059 | 23 |
| 64 | 9036 | 23 |
| 65 | 9013 | 23 |
| 66 | 8989 | 24 |
| 67 | 8965 | 24 |
| 68 | 8941 | 24 |
| 69 | 8917 | 24 |
| 70 | 8892 | 25 |
| 71 | 8867 | 25 |
| 72 | 8842 | 25 |
| 73 | 8817 | 25 |
| 74 | 8791 | 26 |
| 75 | 8765 | 26 |
| 76 | 8739 | 26 |
| 77 | 8712 | 27 |
| 78 | 8685 | 27 |
| 79 | 8658 | 27 |
| 80 | 8631 | 27 |
| 81 | 8603 | 28 |
| 82 | 8575 | 28 |
| 83 | 8547 | 28 |
| 84 | 8518 | 29 |
| 85 | 8488 | 30 |
| 86 | 8458 | 30 |
| 87 | 8428 | 30 |
| 88 | 8397 | 31 |
| 89 | 8365 | 32 |
| 90 | 8332 | 33 |
| 91 | 8299 | 33 |
| 92 | 8265 | 34 |
| 93 | 8230 | 35 |
| 94 | 8194 | 36 |
| 95 | 8157 | 37 |
| 96 | 8118 | 39 |
| 97 | 8077 | 41 |
| 98 | 8034 | 43 |
| 99 | 7988 | 46 |
| 100 | 7939 | 49 |
+------------+------------+----------+
_Remarks on the preceding Table of Alcohol._
The third column of this table exhibits the differences of the specific
gravities, which give the denominator of the fraction for such densities
as are not found sufficiently near in the table; and the difference of
their numerators is the next greatest to the density found in the table.
For example: if the specific gravity of the liquor found for 60° Fahr. =
9605 (the per centage will be between 33 and 34), the difference from
9609 (which is the next greatest number in the table) = 4, and the
fraction is 4/13; therefore the true per centage is 33-4/13. From the
construction of this table the per centage of alcohol by weight may also
be found. For instance: we multiply the number representing the
_volumes_ of alcohol (given in the table for any determinate specific
gravity of the mixture) by the specific gravity of the pure alcohol,
that is, by 7939, and the product is the number of pounds of alcohol in
so many pounds as the specific gravity multiplied by 100 gives. Thus, in
the mixture of 9510 specific gravity, there are 40 measures of alcohol;
hence there are also in 95,100 pounds of this spirit 7939 + 40 = 31·756
pounds of alcohol; and in 100 pounds of the spirits of 0·9510 specific
gravity, 33·39 pounds of alcohol are contained.
As the preceding table gives the true alcoholic content when the portion
of spirit under trial has the normal temperature of 60° Fahr., the
following table gives the per centage of alcohol for the specific
gravities corresponding to the accompanying temperatures.
For example: if we have a spirituous liquor at 80° Fahr., whose specific
gravity is 0·9342, the alcohol present is 45 per cent. of the volume, or
that specific gravity at that temperature is equal to the specific
gravity 0·9427 at the normal temperature of 60° Fahr. This table may
also be employed for every degree of the thermometer and every per
centage, so as to save computation for the intervals. It is evident from
inspection that a difference of 5° Fahr. in the temperature changes the
specific gravity of the liquor by a difference nearly equal to 1 volume
per cent. of alcohol; thus at 35° and 85° Fahr. the very same specific
gravity of the liquor shows nearly 10 volumes per cent. of alcohol more
or less; the same, for example, at 60 and 40 per cent.
+-------+-----------------------------------------------------------+
|Alcohol| Temperature. |
| per +----+----+----+----+----+----+----+----+----+----+----+----+
| cent. | 30°| 35°| 40°| 45°| 50°| 55°| 60°| 65°| 70°| 75°| 80°| 85°|
| | F.| F.| F.| F.| F.| F.| F.| F.| F.| F.| F.| F.|
+-------+----+----+----+----+----+----+----+----+----+----+----+----+
| 0 |9994|9997|9997|9998|9997|9994|9991|9987|9991|9976|9970|9962|
| 5 |9924|9926|9926|9926|9925|9922|9919|9915|9909|9903|9897|9889|
| 10 |9868|9869|9868|9867|9865|9861|9857|9852|9845|9839|9831|9823|
| 15 |9823|9822|9820|9817|9813|9807|9802|9796|9788|9779|9771|9761|
| 20 |9786|9782|9777|9772|9766|9759|9751|9743|9733|9722|9711|9700|
| 25 |9753|9746|9738|9729|9720|9709|9700|9690|9678|9665|9652|9638|
| 30 |9717|9707|9695|9684|9672|9659|9646|9632|9618|9603|9588|9572|
| 35 |9671|9658|9644|9629|9614|9599|9583|9566|9549|9532|9514|9495|
| 40 |9615|9598|9581|9563|9546|9528|9510|9491|9472|9452|9433|9412|
| 45 |9544|9525|9506|9486|9467|9447|9427|9406|9385|9364|9342|9320|
| 50 |9460|9440|9420|9399|9378|9356|9335|9313|9290|9267|9244|9221|
| 55 |9368|9347|9325|9302|9279|9256|9234|9211|9187|9163|9139|9114|
| 60 |9267|9245|9222|9198|9174|9150|9126|9102|9076|9051|9026|9000|
| 65 |9162|9138|9113|9088|9063|9038|9013|8988|8962|8936|8909|8882|
| 70 |9046|9021|8996|8970|8944|8917|8892|8866|8839|8812|8784|8756|
| 75 |8925|8899|8873|8847|8820|8792|8765|8738|8710|8681|8652|8622|
| 80 |8798|8771|8744|8716|8688|8659|8631|8602|8573|8544|8514|8483|
| 85 |8663|8635|8606|8577|8547|8517|8488|8458|8427|8396|8365|8333|
| 90 |8517|8486|8455|8425|8395|8363|8322|8300|8268|8236|8204|8171|
+-------+----+----+----+----+----+----+----+----+----+----+----+----+
The importance of extreme accuracy in determining the density of
alcoholic mixtures in the United Kingdom, on account of the great
revenue derived from them to the State, and their consequent high price
in commerce, induced the Lords of the Treasury a few years ago to
request the Royal Society to examine the construction and mode of
applying the instrument now in use for ascertaining and charging the
duty on spirits. This instrument, which is known and described in the
law as Sikes’s hydrometer, possesses, in many respects, decided
advantages over those formerly in use. The committee of the Royal
Society state, that a definite mixture of alcohol and water is as
invariable in its value as absolute alcohol can be; and can be more
readily, and with equal accuracy, identified by that only quality or
condition to which recourse can be had in practice, namely, specific
gravity. The committee further proposed, that the standard spirit be
that which, consisting of alcohol and water alone, shall have a specific
gravity of 0·92 at the temperature of 62° Fahr., water being unity at
the same temperature; or, in other words, that it shall at 62° weigh
92/100 or 23/25 of an equal bulk of water at the same temperature.
This standard is rather weaker than the old proof, which was 12/13, or
0·923; or in the proportion of nearly 1·1 gallon of the present proof
spirit per cent. The proposed standard will contain nearly one half by
weight of absolute alcohol. The hydrometer ought to be so graduated as
to give the indication of strength; not upon an arbitrary scale, but in
terms of specific gravity at the temperature of 62°.
The committee recommend the construction of an equation table, which
shall indicate the same strength of spirit at every temperature. Thus in
standard spirit at 62° the hydrometer would indicate 920, which in this
table would give proof spirit. If that same spirit were cooled to 40°,
the hydrometer would indicate some higher number; but which, being
combined in the table with the temperature as indicated by the
thermometer, should still give proof or standard spirit as the result.
It is considered advisable, in this and the other tables, not to express
the quality of the spirit by any number over or under proof, but to
indicate at once the number of gallons of standard spirit contained in,
or equivalent to, 100 gallons of the spirit under examination. Thus,
instead of saying 23 over proof, it is proposed to insert 123; and in
place of 35·4 under proof, to insert its difference to 100, or 64·6.
It has been considered expedient to recommend a second table to be
constructed, so as to show the bulk of spirit of any strength at any
temperature, relative to a standard bulk of 100 gallons at 62°. In this
table a spirit which had diminished in volume, at any given temperature,
0·7 per cent., for example, would be expressed by 99·3; and a spirit
which had increased at any given temperature 0·7 per cent., by 100·7.
When a sample of spirit, therefore, has been examined by the hydrometer
and thermometer, these tables will give first the proportion of standard
spirit at the observed temperature, and next the change of bulk of such
spirit from what it would be at the standard temperature. Thus, at the
temperature of 51°, and with an indication (sp. gr.) of 8240, 100
gallons of the spirit under examination would be shown by the first
table to be equal to 164·8 gallons of standard spirit of that
temperature; and by the second table it would appear that 99·3 gallons
of the same spirit would become 100 at 62°, or in reality contain the
164·8 gallons of spirit in that state only in which it is to be taxed.
But as it is considered that neither of these tables can alone be used
for charging the duty (for neither can express the actual quantity of
spirit of a specific gravity of 0·92 at 62° in 100 gallons of stronger
or weaker spirit at temperatures above or below 62°), it is considered
essential to have a third table, combining the two former, and
expressing this relation directly, so that upon mere inspection it shall
indicate the proportion of standard spirit in 100 gallons of that under
examination in its then present state. In this table the quantities
should be set down in the actual number of gallons of standard spirit at
62°, equivalent to 100 of the spirit under examination; and the column
of quantities may be expressed by the term _value_, as it in reality
expresses the proportion of the only valuable substance present. As this
will be the only table absolutely necessary to be used with the
instrument for the purposes of the excise, it may, perhaps, be thought
unnecessary to print the former two.