LIQUORS

The ordinary forms of liquors (namely, whisky, rum, and gin), are
prepared by the distillation of alcoholic infusions. The process of
distillation is preceded either by the conversion of the amylaceous
constituents of grain, first into sugar, then into alcohol, or by the
fermentation of saccharine bodies into alcohol, or, as in the case of
brandy, it may be directly applied to a solution containing alcohol.
_Brandy._–When genuine, brandy is the product of the distillation
of various sorts of rich, light-coloured wines. The most esteemed
quality is prepared in the neighbourhood of Cognac, in the Deux
Charentes district, and in Armagnac; but numerous inferior grades are
manufactured in Rochelle and Bordeaux and in other parts of Southern
France, as well as in Spain and Portugal. In the United States, a
considerable quantity is produced by the distillation of California and
Ohio wine. The fermented marc and lees of grapes are also extensively
utilised in the manufacture of brandy. Most of the liquor known in
commerce under this name, however, is made from the spirit obtained
by the distillation of potatoes, corn, and other grains, which is
subsequently rectified, deodorised, and then suitably flavoured.
In France, the different grades of brandy are known as _eau-de-vie
supérieure_ (the best quality of Cognac); _eau-de-vie ordinaire_
(common, sp. gr. 0·9476); _eau-de-vie de marc_ (chiefly used for mixing
purposes); _eau-de-vie seconde_ (weak and inferior); _eau-de-vie à
preuve de Hollande_ (sp. gr. 0·941); _eau-de-vie à preuve d’huile_ (sp.
gr. 0·9185); _eau-de-vie forte_ (sp. gr. 0·8390); and _esprit-de-vin_
(sp. gr. 0·8610).
The characteristic taste and bouquet of the original wine are to a
considerable extent communicated to the resulting brandy, and upon
these qualities its value is greatly dependent. Many of the remarks
made in regard to the ageing, flavouring and blending of wines equally
apply to brandy, and need not be repeated in this place. When freshly
distilled, it is colourless, its amber tint being either due to the
casks in which it has been stored, or to added caramel. The normal
constituents of genuine brandy are water, alcohol (including small
amounts of butylic, propylic and amylic), various ethers (acetic,
oenanthic, butyric, and valerianic), aldehyde, acetic and tannic
acids, and traces of sugar and the oil of wine. The specific gravity
usually approximates 0·9300 (equivalent to 52 per cent. of alcohol by
volume), it may, however, range from 0·9134 to 0·9381 (from 60 to 48
per cent. of alcohol). Owing to the presence of acetic acid, genuine
brandy usually shows a slightly acid reaction. According to Blyth, the
constituents vary as follows:–total solids, from 1 to 1·5 per cent.;
ash, from ·04 to ·2 per cent.; acids (estimated as tartaric), from ·01
to ·05 per cent.; sugar from 0 to ·4 per cent. A partial examination of
brandy, by König,[111] furnished the following percentages:–specific
gravity, 0·8987; alcohol (by weight), 61·70; extract, 0·645; ash,
0·009. The ingredients found in twenty-five samples of brandy tested
for the New York State Board of Health varied as follows:–specific
gravity, 0·9297 to 0·9615; alcohol (by weight) from 25·39 to 42·96;
extract, from 0·025 to 1·795; ash, from 0·002 to 0·014.
The majority of these samples were certainly abnormal in composition.
Ordonneau[112] has quite recently determined by careful fractional
distillation the proportions of the more important constituents of
cognac brandy twenty-five years old, with the following results, the
quantities being stated in grammes per hectolitre:–aldehyde, 3;
ethylic acetate, 35; acetal, traces; normal propylic alcohol, 40;
normal butylic alcohol, 218·6; amylic alcohol, 83·8; hexylic alcohol,
0·6; heptylic alcohol, 1·5; propionic, butyric and caproic ethers, 3;
oenanthic ether, 4; amines, traces. The large proportions of normal
butylic and amylic alcohols obtained are very significant. It was found
that commercial alcohol, prepared from corn, potatoes and beetroot,
while containing isobutylic alcohol, was entirely free from normal
butylic alcohol, and the difference in flavour between genuine brandy
and brandy distilled from grains would appear to be mainly due to
this fact. Normal butylic alcohol is obtained when fermentation takes
place under the influence of elliptical or wine yeast, whereas the
iso-alcohol is the product of fermentation induced by means of beer
yeast; and it was shown that, by fermenting molasses, etc., with the
aid of wine yeast, a spirit was obtained which much resembled brandy in
colour and flavour.
_Whisky._–Whisky is the spirituous liquor prepared by distilling
fermented infusions of barley, wheat, corn, and other grains. Spirits
that contain over 60 per cent. of alcohol are known as “high wines,”
or common spirits; those containing 90 per cent. of alcohol are often
termed “cologne spirits,” the name whisky being usually given to the
product of a former distillation, containing about 50 per cent. by
weight of alcohol. In Great Britain, the largest amount of whisky is
made in Scotland and Ireland; in the United States, the principal
supply comes from the States of Illinois, Ohio, Indiana, Kentucky
(Bourbon Co.), and Pennsylvania (Monongahela Co.). The grains taken
differ greatly in composition. In Scotland and Ireland, malted barley
(pure, or mixed with other grain) is extensively employed; in the
preparation of Bourbon, partially malted corn and rye are taken,
while, for Monongahela whisky, only rye (with 10 per cent. of malt)
is used. The essential features of whisky-making are, first, the
conversion of the starch of the grain into dextrine and glucose,
which takes place in the process of _mashing_; the change being due
to the action of the nitrogenous principle, _diastase_ (formed during
the germination of the gain); then, the transformation of the sugar
into alcohol and carbonic acid by fermentation, which is induced by
the addition of yeast; and, finally, the concentration of the alcohol
by distillation. The quality of whisky is much affected by the nature
of the grain from which it is prepared, and by the care exercised in
its manufacture, more particularly in the process of distillation.
The most injurious ingredient in distilled spirits is commonly known
as “fusel oil,” which term comprises several products of alcoholic
fermentation, possessing a higher boiling point than ethylic alcohol,
and consisting chiefly of amylic alcohol, accompanied by small
proportions of butylic and propylic alcohols. Several varieties of
fusel oil exhibiting distinctive properties are met with, but that
obtained from potato-spirit is the most common. As a rule, the spirits
prepared from malted grain contain the smallest proportion. In the
manufacture of whisky, a danger of promoting the formation of fusel
oil is incurred by carrying on the distillation to the furthest
point, in order to obtain the greatest possible quantity of alcohol.
In Great Britain, the fermented mash is removed from the remaining
grain before its introduction into the still; but in this country the
entire mash is occasionally taken, by which means a larger yield of
alcohol is supposed to be effected. This practice is evidently open to
the objection that the solid matters of the wort are liable to suffer
destructive distillation, and engenders the formation of fusel oil.
Another result, sometimes experienced, is the imparting of a smoky
flavour to the product, which was originally intentionally communicated
to the famous “poteen” whisky of Ireland, by using malt dried by
means of burning turf. This quality is said to be still artificially
obtained by the use of creosote. Genuine whisky, when recently
made, is nearly colourless; but, if preserved in casks, it gradually
acquires a brownish colour. It contains minute quantities of tannic
acid, and ethylic and amylic acetates and valerianates. The specific
gravity generally ranges between 0·9220 and 0·9040, corresponding to
48 and 56 per cent. of alcohol. The solid extract in whisky is usually
below 1 per cent., and the total volatile acids under 0·1 per cent.
In regard to the average composition of whisky, chemical literature
furnishes but very meagre data. The examination of a large number of
samples of ordinary American whisky in 1881, for the New York State
Board of Health, gave the following results:–Specific gravity ranged
from 0·9018 to 0·9645; alcohol (by weight) from 23·75 to 52·58; solid
residue, from 0·100 to 0·752; ash, from 0·0020 to 0·0280. Several
samples of rye whisky, examined by Mr. Green,[113] showed alcohol (by
weight) from 32·50 to 51·20; tannic acid, 0·0003; acetic acid, 0·0012
to 0·002; sugar, 0·002 to 0·005; solid residue, 0·160 to 0·734.
_Rum._–Rum is obtained by the distillation of the fermented juice
of sugar-cane or of molasses; a very considerable proportion of the
article bearing this name is, however, made from grain spirit. In
France and Germany the mother-liquor remaining after the extraction
of beet-sugar, is utilised in the manufacture of a spirituous liquor
greatly resembling rum in properties. The characteristic odour and
taste of the liquor are mainly due to the presence of ethylic butyrate,
and are frequently factitiously communicated to its imitations by
the direct addition of this ether or of butyric acid. Grain spirit
is also sometimes treated with pineapples, which likewise impart the
distinctive flavour. Rum is chiefly produced in the West Indies, and
in North America. The specific gravity ranges from 0·874 to 0·926;
alcohol, from 50 to 70 per cent.; solid residue, from 0·7 to 1·50 per
cent; ash, under 0·10 per cent.[114]
The following are the results obtained by Berkhurts, from the analysis
of various samples of genuine and artificial Jamaica rum:[115]–
—————–+———-+———-+———+——-
| Specific |Alcohol by| Total |
Source. | Gravity. | Weight. | Solids. | Ash.
—————–+———-+———-+———+——-
London | 0·885 | 61·38 | 0·668 | 0·023
Glasgow | 0·875 | 61·38 | 4·800 | 0·089
Bremen | 0·875 | 74·07 | 0·568 | 0·031
Directly imported| 0·910 | 51·33 | 2·047 | 0·098
Artificial | .. | 38·94 | 0·469 | 0·033
Artificial | .. | 58·86 | 0·926 | 0·021
—————–+———-+———-+———+——-
The variations in the composition of commercial rum would seem to be so
great that little information of value concerning its authenticity is
to be derived from analyses of a general character.
_Gin._–Genuine Holland gin is a spirit prepared by the distillation
of fermented grain infusions (rye and malted barley), flavoured with
juniper berries, or oil of turpentine. Formerly the flavouring was
directly introduced into the still together with the mash, but the
more recent practice is to add salt, water, and juniper berries to
the distilled grain spirit, and then re-distil the mixture. Numerous
other aromatic substances are likewise employed in the manufacture of
gin, among which are coriander, cardamom, and caraway seeds, orris,
angelica, and calamus roots, cassia, bitter-almonds, sweet fennel, etc.
Cayenne pepper, sugar, and acetic acid, are said to be also frequently
added to gin. Gin doubtless possesses more of an artificial character
than any other spirit. It is safe to assert that the great bulk of the
drink sold under the name is simply grain-spirits flavoured with some
of the preceding aromatics. On the other hand, the flavouring agents
employed are not, as a rule, harmful in their effects, so that the
quality of the liquor is mainly dependent upon the extent to which the
spirits used have been rectified. It is difficult to define “pure
gin,” since, owing to its compound character, it varies in composition
according to the method of manufacture followed by each individual
distiller. The variations found from the examination of twenty-five
samples of the commercial article, tested by the New York State Board
of Health, were as follow:[116]–Specific gravity, from 0·9302 to
0·9694; alcohol (by weight), from 18·64 to 44·33; solid residue, from
0·018 to 0·772; ash, from 0·001 to 0·019.
_Adulteration of liquors._–Although it is notorious that the more
common varieties of spirituous liquors are sophisticated, the practices
resorted to are unfortunately usually of a character that does not
permit of positive detection, and, unless an actual adulteration, such
as the addition of some substance foreign to the genuine liquor, has
been made, a chemical examination alone is frequently inadequate to
distinguish between the true and the factitious article. In fact, the
ordinary physical qualities, such as odour and taste, are often of
greater service in determining the genuineness of distilled spirits
than more scientific tests. The most prevalent form of sophistication
with brandy, rum, and gin, is their artificial imitations; the direct
addition of substances deleterious to health being of comparatively
unfrequent occurrence. It is usual to employ a certain proportion of
the genuine liquor in the fabrication of its imitation. An apparent
objection to this species of adulteration is that grain spirits are
liable to be used as the basis of the fictitious product, which is
therefore apt to be contaminated with fusel oil, a compound producing
toxic effects in a proportion fifteen times greater than ordinary
ethylic alcohol.
In the United States, whisky is probably less subjected to serious
sophistication than other spirituous drinks. While the blending
of this liquor (i. e. the mixing of new and old grades) is almost
universally practised by the refiner, and while the retail dealer often
reduces its alcoholic strength by the addition of water, there is very
little ground for the belief that, in this country, whisky is subjected
to noxious admixture to any great extent.
A very large number of recipes have been published for the manufacture
of spurious liquors; the following are characteristic, and will
indicate their general nature:–
_For Brandy_:–
Cologne spirits (reduced to proof) 40 galls.
Oil of cognac 1/6 oz.
Burnt sugar colouring 1½ pint.
Tannin ¼ oz.
Brandy essence 1 part.
Alcohol 1000 parts.
Water 600 „
The compound known as “Brandy essence” consists of oil of grapes, 5
parts; acetic ether, 4 parts; tincture of allspice, 1 part; tincture of
galls, 3 parts; and alcohol, 100 parts. “Oil of cognac” is a mixture of
amylic alcohol and oenanthic ether.
According to M. Duplais, the best imitation of Cognac is the
following:–
Alcohol (85 per cent.) 54 litres.
Rum (good quality) 2 „
Syrup of raisins 3 „
Infusion of green walnut hulls 2 „
Infusion of the shells of bitter almonds 2 „
Catechu, in powder 15 grammes.
Balsam of tolu 6 „
Pure water 37 litres.
Mix and colour with caramel.
New Cognac, Montpellier, Saintonge, and other brandies are aged and
improved by adding to every 100 litres: old rum, 2 litres; old kirsch,
1-3/4 litres; infusion of green walnut hulls, 3/4 litre; syrup of
raisins, 2 litres.
A compound sold as “London Brandy Improver” consists of sugar syrup,
acetic ether and essence of cayenne, coloured with caramel.
_Whisky_:–
(Rye) Proof spirit 50 galls.
Pelargonic ether 2 oz.
Pear oil 1 „
Oil of wintergreen (dissolved in alcohol) 10 drops.
Acetic ether 4 oz.
Oil of cloves (dissolved in acetic ether) 4 drops.
(Scotch) Alcohol (95 per cent.) 46 galls.
Scotch whisky 8 „
Water 18 „
Honey (3 lbs. in 1½ gall. water)
Creosote 5 drops.
Acetic acid 2 oz.
Pelargonic ether 1 „
Ale 1 gall.
(Irish) Spirits 30 galls.
Irish whisky 5 „
Old ale ½ „
Creosote (dissolved in acetic acid) 4 drops.
Pelargonic ether 1 oz.
The preparation met with in commerce under the name of “pelargonic
ether” appears to be identical with oenanthic ether.
_Rum_:–
Rectified spirits 6 quarts.
Jamaica rum 22 „
Rum essence 1½ oz.
Vanilla essence 1/10 „
Water 2 quarts.
St. John’s bread 1½ oz.
Raisins 1½ „
Proof spirits 40 galls.
Rum essence ½ pint.
Sugar colouring ½ „
Sugar syrup 1 quart.
“Rum essence” is composed of butyric ether, 15 parts; acetic ether,
2 parts; vanilla tincture, 2 parts; essence of violets, 2 parts; and
alcohol, 90 parts.
_Gin_:–
Corn spirits 80 galls.
Oil of turpentine 1 pint.
Oil of juniper 8 oz.
Salt 21 lbs.
Water 35 galls.
Oil of caraway ½ oz.
Oil of sweet fennel ¼ „
Cardamoms 8 „
Distil over, 100 galls.
The chemical examination of distilled spirits is ordinarily limited
to a determination of the alcohol, solid residue, ash, and volatile
acids, coupled with special qualitative and quantitative tests for any
particular adulterants, the presence of which may be suspected.
(_a_) _Alcohol._–In properly distilled liquors, a fairly approximate
estimation of their alcoholic strength is effected by the specific
gravity determination, which is best made by means of the special
gravity bottle. In the case of spirituous liquors which contain
extractive matters, it is necessary to first separate the alcohol
present by the process of distillation, and then determine the density
of the distillate when made up to the volume originally taken. The
following table gives the percentages of alcohol by weight and by
volume, and of water by volume, for specific gravities at 15°.[117]
The percentages of alcohol in the table are calculated for the
temperature of 15°. The necessary correction for differences of
temperature at which the determination is made is obtained by
multiplying the number of degrees above or below 15°, by 0·4, and
adding the product to the percentage shown by the table, when the
temperature is lower than 15°, and deducting it when it is above.
Percentage of alcohol, by weight and by volume, and of water by
volume, for specific gravity at 15°; water at same temperature being
the unit:–
———+————————-
| PERCENTAGE.
+———+—————
| By | By
| Weight. | Volume.
Specific +———+——+——–
Gravity. | Alc. | Alc. | Water.
———+———+——+——–
1·0000 | 0· | 0 | 100·
0·9985 | 0·80 | 1 | 99·05
0·9970 | 1·60 | 2 | 98·11
0·9956 | 2·40 | 3 | 97·17
0·9942 | 3·20 | 4 | 96·24
0·9928 | 4·00 | 5 | 95·30
0·9915 | 4·81 | 6 | 94·38
0·9902 | 5·61 | 7 | 93·45
0·9890 | 6·43 | 8 | 92·54
0·9878 | 7·24 | 9 | 91·62
0·9867 | 8·06 | 10 | 90·72
0·9855 | 8·87 | 11 | 89·80
0·9844 | 9·69 | 12 | 88·90
0·9833 | 10·51 | 13 | 88·00
0·9822 | 11·33 | 14 | 87·09
0·9812 | 12·15 | 15 | 86·19
0·9801 | 12·98 | 16 | 85·29
0·9791 | 13·80 | 17 | 84·39
0·9781 | 14·63 | 18 | 83·50
0·9771 | 15·46 | 19 | 82·60
0·9761 | 16·29 | 20 | 81·71
0·9751 | 17·12 | 21 | 80·81
0·9741 | 17·96 | 22 | 79·92
0·9731 | 18·79 | 23 | 79·09
0·9721 | 19·63 | 24 | 78·13
0·9711 | 20·47 | 25 | 77·23
0·9700 | 21·31 | 26 | 76·33
0·9690 | 22·16 | 27 | 75·43
0·9679 | 23·00 | 28 | 74·53
0·9668 | 23·85 | 29 | 73·62
0·9657 | 24·70 | 30 | 72·72
0·9645 | 25·56 | 31 | 71·80
0·9633 | 26·41 | 32 | 70·89
0·9620 | 27·27 | 33 | 69·96
0·9607 | 28·14 | 34 | 69·04
0·9595 | 29·01 | 35 | 68·12
0·9582 | 29·88 | 36 | 67·20
0·9568 | 30·75 | 37 | 66·26
0·9553 | 31·63 | 38 | 65·32
0·9538 | 32·52 | 39 | 64·37
0·9522 | 33·40 | 40 | 63·42
0·9506 | 34·30 | 41 | 62·46
0·9490 | 35·18 | 42 | 61·50
0·9473 | 36·09 | 43 | 60·58
0·9456 | 37·00 | 44 | 59·54
0·9439 | 37·90 | 45 | 58·61
0·9421 | 38·82 | 46 | 57·64
0·9403 | 39·74 | 47 | 56·66
0·9385 | 40·66 | 48 | 55·68
0·9366 | 41·59 | 49 | 54·70
0·9348 | 42·53 | 50 | 53·72
0·9328 | 43·47 | 51 | 52·73
0·9308 | 44·41 | 52 | 51·74
0·9288 | 45·37 | 53 | 50·74
0·9267 | 46·33 | 54 | 49·74
0·9247 | 47·29 | 55 | 48·74
0·9226 | 48·26 | 56 | 47·73
0·9205 | 49·24 | 57 | 46·73
0·9183 | 50·21 | 58 | 45·72
0·9161 | 51·20 | 59 | 44·70
0·9139 | 52·20 | 60 | 43·68
0·9117 | 53·19 | 61 | 42·67
0·9095 | 54·20 | 62 | 41·65
0·9072 | 55·21 | 63 | 40·63
0·9049 | 56·23 | 64 | 39·60
0·9026 | 57·25 | 65 | 38·58
0·9002 | 58·29 | 66 | 37·54
0·8978 | 59·33 | 67 | 36·51
0·8954 | 60·38 | 68 | 35·47
0·8930 | 61·43 | 69 | 34·44
0·8905 | 62·50 | 70 | 33·39
0·8880 | 63·58 | 71 | 32·35
0·8855 | 64·64 | 72 | 31·30
0·8830 | 65·72 | 73 | 30·26
0·8804 | 66·82 | 74 | 29·20
0·8778 | 67·93 | 75 | 28·15
0·8752 | 69·04 | 76 | 27·09
0·8725 | 70·16 | 77 | 26·03
0·8698 | 71·30 | 78 | 24·96
0·8671 | 72·43 | 79 | 23·90
0·8644 | 73·59 | 80 | 22·83
0·8616 | 74·75 | 81 | 21·76
0·8588 | 75·91 | 82 | 20·68
0·8559 | 77·09 | 83 | 19·61
0·8530 | 78·29 | 84 | 18·52
0·8500 | 79·51 | 85 | 17·42
0·8470 | 80·72 | 86 | 16·32
0·8440 | 81·96 | 87 | 15·23
0·8409 | 83·22 | 88 | 14·12
0·8377 | 84·47 | 89 | 13·01
0·8344 | 85·74 | 90 | 11·88
0·8311 | 87·04 | 91 | 10·76
0·8277 | 88·37 | 92 | 9·62
0·8242 | 89·72 | 93 | 8·48
0·8206 | 91·08 | 94 | 7·32
0·8169 | 92·45 | 95 | 6·16
0·8130 | 93·89 | 96 | 4·97
0·8089 | 95·35 | 97 | 3·77
0·8046 | 96·83 | 98 | 2·54
0·8000 | 98·38 | 99 | 1·28
0·7951 | 100·00 | 100 | 0·00
———+———+——+——–
(_b_) _Solid residue._–This is determined by evaporating 100 c.c. of
the liquor in a tared platinum dish, until constant weight is obtained.
(_c_) _Ash._–The proportion of ash is found by the incineration of the
solid residue. If the presence of poisonous metallic adulterants (such
as copper or lead) is suspected, a further examination of the ash is
necessary.
(_d_) _Acids._–The acidity of distilled liquors is generally due to
minute quantities of acetic acid, and can be estimated by means of
1/10th normal soda solution.
Any mineral acid (_e.g._, sulphuric acid) supposed to be present is to
be sought for in the residue remaining, after the distillation process
employed in the determination of alcohol.
The presence of fusel oil in liquors is sometimes quite readily
detected, by first removing the ethylic alcohol by gentle evaporation,
and then inspecting the odour and taste of the still warm residue.
The suspected liquor may also be agitated with an equal volume of
ether, water added, and the ethereal stratum removed by means of a
pipette, and concentrated by evaporation; the residue is to be examined
for amylic alcohol. When distilled with a mixture of sulphuric and
acetic acids, amylic alcohol is converted into amylic acetate, which
may be recognised by its characteristic pear-like odour; or, the
amylic alcohol can be transformed into valerianic acid (which also
possesses a distinctive odour) by oxidation with sulphuric acid and
potassium dichromate. Another simple qualitative test for fusel oil
consists in first decolorising a small quantity of the liquor under
examination with animal charcoal, adding a few drops of hydrochloric
acid, and then a little freshly distilled and colourless aniline
oil, when, in presence of fusel oil, it will be observed that the
aniline compound acquires a perceptible rose tint as it falls to the
bottom of the liquid. The quantitative determination of fusel oil
presents some difficulties. A very ingenious method has been suggested
by Marquardt.[118] It consists essentially in first agitating the
sample with chloroform, draining off the solution obtained, washing
it by repeated shaking with water, and then treating it at 85° with a
mixture of 5 parts potassium dichromate, 2 parts sulphuric acid, and
30 parts of water. The valerianic acid thus formed is now separated
by distilling the mixture of water and chloroform. The distillate is
digested with barium carbonate, next concentrated by evaporation,
and then filtered, and divided into two equal portions. One portion
is evaporated to dryness, the residue taken up with water containing
a little nitric acid, and the amount of barium present determined
by precipitation with sulphuric acid. In the other portion, the
chlorine originating from a partial oxidation of the chloroform, is
to be estimated. The amount of barium combined with the chlorine, is
deducted from the total quantity obtained; the remainder represents the
proportion in combination with the fatty acids formed by oxidation. Of
these, valerianic acid largely predominates; and the amount of barium
valerianate [Ba_{2} (C_{2}H_{3}O_{2})] found is calculated to its
equivalent in amylic alcohol. Capsicum, creosote, etc., are isolated by
treating the sample with ether or benzole, and testing the odour and
taste of the evaporated solutions so prepared.
Creosote gives a blue colour with ferric chloride solution; and the
exceedingly pungent vapours evolved upon heating a residue containing
capsicum are equally characteristic. The presence of tannin in
distilled spirits, which is mostly derived from their preservation in
casks, is recognised by the formation of a bluish-black colour upon the
addition of ferric solutions. The identification of the various ethylic
and amylic ethers used in the preparation of factitious liquors is a
matter of some difficulty. Their presence is most readily detected by
means of their characteristic odour, which is developed upon adding a
little sodium hydroxide to the sample, evaporating the mixture over
the water-bath almost to dryness, and then adding a small quantity of
sulphuric acid. Another means of ascertaining the nature of the organic
ethers present in spirits is to first remove the ethylic alcohol
contained by a partial distillation with an alkaline solution, and
then acidulate the remaining liquid with sulphuric acid, and repeat
the distillation, when the volatile fatty acids originally contained
in the ethers will be found in the distillate; their identity is to be
established by means of their characteristic properties. Nitrous ether
(which compound is not contained in genuine liquors) may be detected
by partially distilling the sample and adding a mixture of potassium
iodide, starch paste, and acetic acid to the first portion of the
distillate, the production of a blue colour indicating its presence. As
previously remarked, the exercise of the ordinary senses is frequently
of greater value in judging the quality of liquors than the results of
chemical tests. Many of the organic ethers employed in the manufacture
of artificial liquors are identical with those contained in the genuine
article, and it is obvious that, in such instances, no distinction can
be made between them.