is discussed in the article FERMENTATION, and the manufacture
of alcohol from fermented liquors in the article SPIRITS.
The qualitative composition of ethyl alcohol was ascertained by
A. L. Lavoisier, and the quantitative by N. T. de Saussure in
1808. Sir Edward Frankland showed how it could be derived
from, and converted into, ethane; and thus determined it
to be ethane in which one hydrogen atom was repiaced by a
hydroxyl group. Its constitutional formula is therefore
CH3.CH2.OH. It may be synthetically prepared by any
of the general methods described in the article ALCOHOLS.
Pure ethyl alcohol is a colourless, mobile liquid of an agreeable
odour. It boils at 78.3 deg. C. (760 mm.); at -90 deg. C. it
is a thick liquid, and at -130 deg. it solidifies to a white
mass. Its high coefficient of thermal expansion, coupled with
its low freezing point, renders it a valuable thermometric
fluid, especially when the temperatures to be measured are
below -39 deg. C., for which the mercury thermometer cannot be
used. It readily inflames, burning with a blue smokeless flame,
and producing water and carbon dioxide, with the evolution of
great heat; hence it receives considerable application as a
fuel. It mixes with water in all proportions, the mixing
being attended by a contraction in volume and a rise in
temperature; the maximum contraction corresponds to a mixture
of 3 molecules of alcohol and 1 of water. Commercial alcohol
or ``spirits of wine'' contains about 90% of pure ethyl
alcohol, the remainder being water. This water cannot be
entirely removed by fractional distillation, and to prepare
anhydrous or ``absolute'' alcohol the commercial product
must be allowed to stand over some dehydrating agent, such as
caustic lime, baryta, anhydrous copper sulphate, &c., and then
distilled. Calcium chloride must not be used, since it forms
a crystalline compound with alcohol. The quantity of alcohol
present in an aqueous solution is determined by a comparison
of its specific gravity with standard tables, or directly by
the use of an alcoholometer, which is a hydrometer graduated so
as to read per cents by weight (degrees according to Richter)
or volume per cents (degrees according to Tralles). Other
methods consist in determining the vapour tension by means
of the vaporimeter of Geissler, or the boiling point by the
ebullioscope. In the United Kingdom ``proof spirit'' is
defined as having a specific gravity at 51 deg. of 12/13 (.92308)
compared with water at the same temperature. The ``quantity
at proof'' is given by the formula:-- quantity of sample
X (degrees over or under proof + 100) divided by 100.
The presence of water in alcohol may be detected in several
ways. Aqueous alcohol becomes turbid when mixed with
benzene, carbon disulphide or paraffin oil; when added to
a solution of barium oxide in absolute alcohol, a white
precipitate of barium hydroxide is formed. A more delicate
method consists in adding a very little anthraquinone and
sodium amalgam; absolute alcohol gives a green coloration,
but in the presence of minute traces of water a red coloration
appears. Traces of ethyl alcohol in solutions are detected
and estimated by oxidation to acetaldehyde, or by conversion
into iodoform by warming with iodine and potassium hydroxide.
An alternative method consists in converting it into ethyl
benzoate by shaking with benzoyl chloride and caustic soda.
Alcohol is extensively employed as a solvent; in fact,
this constitutes one of its most important industrial
applications. It dissolves most organic compounds, resins,
hydrocarbons, fatty acids and many metallic salts, sometimes
forming, in the latter case, crystalline compounds in which
the ethyl alcohol plays a role similar to that of water of
crystallization. This fact was first noticed by T. Graham, and,
although it was at first contradicted, its truth was subsequently
confirmed. In general, gases dissolve in it more readily
than in water; 100 volumes of alcohol dissolve 7 volumes of
hydrogen, 25 volumes of oxygen and 16 volumes of nitrogen.
Reactions.
Potassium and sodium readily dissolve in ethyl alcohol
with the production of alcoholates of the formula C2 H5
OK(Na). These are voluminous white powders. Sulphuric acid
converts it into ethyl sulphuric acid (see ETHER, and sulphur
trioxide gives carbyl sulphate. The phosphorous haloids
give the corresponding ethyl haloid. Ethyl chloride (from
the phosphorus chlorides and alcohol) is an ethereal liquid
boiling at 12.5 deg. C., soluble in alcohol, but sparingly so in
water. Oxidation of ethyl alcohol gives acetaldehyde
and acetic acid. Chlorine oxidizes it to acetaldehyde,
and under certain conditions chloral (q.v.) is formed.
Industrial alcohol.
In almost all countries heavy taxes are levied on manufactured
alcohol mainly as a source of revenue. In the United Kingdom
the excise duty is eleven shillings per proof gallon of alcohol,
while the customs duty is eleven shillings and fivepence; the
magnitude of these imposts may be readily understood when one
remembers that the proof gallon costs only about sevenpence to
manufacture. The great importance of alcohol in the arts has
necessitated the introduction of a duty-free product which is
suitable for most industrial purposes, and at the same time
is perfectly unfit for beverages or internal application.
Methylated spirit.
In the United Kingdom this ``denaturized'' alcohol is known
as methylated spirit as a distinction from pure alcohol or
``spirits of wine.'' It was first enacted in 1855 that methylated
spirit, a specific mixture of pure alcohol and wood- naphtha,
should be duty-free; the present law is to be found in the
Customs and Inland Revenue Act of 1890, and the Finance Act
(sect. 8) of 1902. From 1858 to 1861 methylated spirit was
duty-free when it was required for manufacturing processes,
and the methylation or ``denaturizing'' was carried out in
accordance with a prescribed process. During the next three
decades (1861-1891) the law was extended, and methylated spirit
was duty-free for all purposes except for use as beverages and
internal medicinal applications. This spirit (``unmineralized
methylated spirit'') consisted of 90 parts of alcohol of
60-66 over-proof (91-95% of pure alcohol) and 10 parts of
wood-naphtha. It was found, however, that certain classes
were addicted to drinking this mixture, and since 1891 the
sale of such spirit has been confined to manufacturers who
must purchase it in bulk from the ``methylators.'' For retail
purposes the ``ordinary'' methylated spirit is mixed with .357%
of mineral naphtha, which has the effect of rendering it quite
undrinkable. The Finance Act of 1902 allows a manufacturer to
obtain a license which permits the use of duty-free alcohol,
if he can show that such alcohol is absolutely essential for
the success of his business, and that methylated spirit is
unsuitable. Notwithstanding this permission there have
been many agitations on the part of chemical manufacturers
to obtain a less restricted use of absolute alcohol, and
in 1905 an Industrial Alcohol Committee was appointed to
receive evidence and report as to whether any modification
of the present law was advisable. In the United States
the same question was considered in 1896 by a Joint Select
Committee on the use of alcohol in the manufactures and arts.
Reference should be made to the reports of these committees
for a full account of the use, manufacture and statistics
of ``denaturized'' spirits in various European countries.
In Germany, the use of duty-free spirit is only allowed to state
and municipal hospitals, and state scientific institutions,
and for the manufacture of fulminates, fuzes and smokeless
powders. The duty-free ``denaturized'' spirits may be
divided into two groups--``completely denaturized'' and
``incompletely denaturized.'' In the first category there
are two varieties:--(1) A mixture of 100 litres of spirit and
2 1/2 litres of a mixture of 4 parts of wood-naphtha and 1 of
pyridine bases; this spirit, the use of which is practically
limited to heating and lighting purposes, may be mixed with 50
grs. of lavender or rosemary, in order to destroy the noxious
odour of the pyridine bases. (2) A mixture of 100 litres of
spirit, 1 1/4 litres of the naphtha-pyridine mixture described
above, 1/4 litre of methyl violet solution, and from 2 to
20 litres of benzol; this fluid is limited to combustion
in motors and agricultural engines. The second category,
or ``incompletely denaturized'' spirits, include numerous
mixtures. The ``general'' mixture consists of 100 litres of
spirit, and 5 litres of wood spirit or 1/2 litre of pyridine.
Of the ``particular'' varieties, we can only notice those used
in the colour industry. These consist of 100 litres of spirit
mixed with either 10 litres of sulphuric ether, or 1 litre of
benzol, or 1/2 litre of turpentine, or .025 litre of animal oil.
The German regulations are apparently based on a keen appreciation
of the fact that while one particular denaturizing agent may
have little or no effect on one industry, yet it would be
quite fatal to the success of another; there is consequently
a great choice of denaturizing agents, and in certain cases
it is sufficient to mix the alcohol with a reagent necessary
for the purpose in hand, or even with a certain amount
of the final product, it being only necessary to satisfy
the state that the spirit is not available as a beverage.
In France, the general denaturizing agent is wood-spirit of
at least 58 over-proof, and containing 25% of acetone and
2.5% of ``impurites pyrogenees''; 10 litres of this spirit
denaturizes 100 litres of alcohol. This mixture is supplied
to manufacturers and corresponds to the British unmineralized
methylated spirit; but the regulations are more stringent. When
sold for lighting and heating purposes, it is further admixed
with 0.5% of heavy benzene boiling at 150 deg. -200 deg. C. Provisions
are also made for special denaturizing processes as in Germany.
In America the internal revenue tax on denaturized alcohol
(formerly duty-free only to scientific institutions)
was removed by Congress in 1906 (act of June 7th).
Pharmacology, Toxicology and Therapeutics of Alcohol.--
Alcohol is of great medicinal value as a solvent, being
used to form solutions of alkaloids, resins, volatile oils,
iodoform, &c. In strength of about 10% and upwards it is an
antiseptic. If applied to the skin it rapidly evaporates,
thereby cooling the skin and diminishing the amount of sweat
excreted. This refrigerant and anhidrotic action is employed to
soothe many forms of headache by bathing the forehead with eau de
Cologne. If, on the other hand, the alcohol be rubbed into the
skin, or if its evaporation be prevented--as by a watch-glass--it
absorbs water from the tissues and thus hardens them.
Thoroughly rubbed into the skin alcohol dilates the blood-
vessels and produces a mild counter-irritant effect. Many
alcoholic liniments are therefore employed for the relief of
pain, especially muscular pains, as in lumbago and other forms
of so-called ``muscular rheumatism.'' Given internally in
small quantities and in sufficient dilution, alcohol causes
dilatation of the gastric blood-vessels, increased secretion
of gastric juice, and greater activity in the movements of
the muscular layers in the wall of the stomach. It also tends
to lessen the sensibility of the stomach and so may relieve
gastric pain. In a 50% solution or stronger--as when neat
whisky is taken--alcohol precipitates the pepsin which is
