May 25, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
917 
substitute for cantharides. An instance of tlie effect 
of these hairs is quoted from a French journal in 
Cliristison on Poisons (p. 017), “A child, ten years 
old, had a common blister applied to the neck and 
spine as a remedy for deafness, and four days after¬ 
wards her mother dressed the abrased skin with the 
leaves of beet-root, from which she had previously 
shaken a great number of caterpillars. The child 
soon complained of insupportable itching and burn¬ 
ing in the part, and endeavoured to tear off the 
dressings. The mother persevered, however, and 
the child died in two days of gangrene of the whole 
integuments of the back. The surgeon who saw the 
child on the last day of her life ascribed the gan¬ 
grene to the insects mentioned above, and states that 
they possess the power of exciting erysipelas when 
applied even to the sound skin.” Although not 
found in Britain, these caterpillars are common on 
the Continent, where they often become a very great 
nuisance, on account of their urticating hairs. They 
abounded in the woods which, before the late war, 
skirted the city of Paris. In the Bois de Boulogne 
they considerably damped the ardour of citizens 
when they were abundant. When the webs were 
more than usually plentiful, as in 1865, parts of the 
wood were closed by the authorities against pro- 
menaders. In the southern departments of France 
the danger of coming in contact with “ chenille 
veneneuse ” is so much considered that persons com¬ 
pelled by business to be near a tree infested by them 
are recommended to envelope their bodies in oiled 
linen. For further particulars on this subject we 
may refer to an article on “ Processionary Moths,” 
by the Ilev. W. W. Spicer, in ‘ Science Gossip,’ 
No. 77. (1871.) 
Chapters far §tui>cnts. 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDEN, D.SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
Spiritus Rectificatus. 
[§ Alcohol C 2 H 6 0, with sixteen per cent, of water.] 
Specif, grav. *838. 
A moderately dilute solution of sugar to which 
some yeast has been added, kept at a temperature 
of 70° to 80° F. very speedily effervesces from the 
escape of carbonic anhydride; and if after the 
fermentation is over, the liquid is submitted to 
repeated distillation, the more volatile portion being 
each time collected, alcohol in an impure state is 
ultimately obtained. If cane sugar is employed, it 
is first converted into glucose, 
C 12 H 22 0h + HoO = 2C 6 H 12 0 6 . 
And this subsequently splits up. 
C 6 H 12 0 6 = 2C0 2 + 2C 2 H 6 0. 
But the reaction is in reality much more complex 
than such an equation would indicate, glycerine and 
succinic acid having been detected in the residue of 
the distillation, and the development of the yeast 
demands the production of cellulose and fatty mat¬ 
ter. Moreover, as ordinarily conducted, the fermen¬ 
tation of saccharine solutions yields small quantities 
of other alcohols, of which some are homologous 
with ordinary alcohol, as for instance i 
Propylic alcohol .... C 3 H 3 0. 
Butjdic „ .... C 4 H 10 O. 
Amy lie ,, .... C 5 H 12 0. 
Others, though possessing the same composition 
as these bodies, possess different properties ; are in 
fact isomeric with them. These liquids are less vola;- 
tile than ordinary alcohol, and are almost entirely 
separated by the process of rectification. They con¬ 
stitute the liquid known as ‘ fousel oil.’ The test of the- 
B. P. is intended to indicate that traces only remain,. 
[§ Four fluid ounces with thirty grain-mea¬ 
sures of the volumetric solution of nitrate off 
| silver exposed for twenty-four hours to bright light,, 
and then decanted from the black powder (metallic- 
silver) which has formed, undergoes no further 
change when again exposed to light with more of 
the test.] 
When alcohol and water are mixed, the liquid be¬ 
comes warm, an effervescence occurs from the expul¬ 
sion of the air which the water held in solution; 
and after the mixture has cooled, it will be found 
not to measure the sum of the volumes of the two 
liquids ; contraction has taken place. Consequently, 
the strength of a given sample of dilute alcohol 
cannot be inferred from its specific gravity, which is 
greater than the calculated mean. The rectified 
spirit of the Pharmacopoeia is a mixture of alcohol 
and water containing 84 parts per cent, by weight of 
the former. It is also often spoken of as being 56° 
over proof,—this means that in order to reduce it to 
the strength of proof spirit 100 volumes must be mixed 
with water till, after contraction, they measure 156 
volumes. Nearly 60 volumes of water are necessary 
( for this purpose. 
To detect alcohol in aqueous fluids, it is sometimes 
sufficient simply to saturate with dry carbonate of 
i potassium, when the alcohol separates and floats 
I upon the surface, and may be recognized by its in- 
i flammability and other properties. But when the 
quantity is too minute to be detected in this way, 
Lieben’s test may be used. Add to the liquid a grain 
or so of iodine and a few drops of caustic soda; warm 
gently, and then allow it to stand for a time. Iodo¬ 
form is deposited as a yellowish crystalline substance, 
CoH fi O + 4I 2 + 6NaHO = 
CHI 3 + NaCH0 2 + 5NaI + 5H 2 0 
The iodoform may be recognized when mere traces- 
are produced by examining the deposit under the 
microscope. The crystals present the appearance of 
hexagonal plates, or sometimes six-rayed stars. It 
is said that 1 of alcohol in 2000 of water may be de¬ 
tected by this test. 
To obtain absolute alcohol , that is alcohol free 
i from water, the Pharmacopoeia directs to remove 
the first greater portion of the water from rectified 
spirit by means of carbonate of potassium, and 
afterwards to dehydrate by burnt lime. To deprive 
it of the last traces of water, the spirit, after the 
foregoing treatment, should be boiled with quick¬ 
lime for about an hour in a flask with inverted con-^ 
denser, and then distilled. The specific gravity ot 
absolute alcohol at 60° F. is ‘7939, and boiling- 
point, under the standard pressure of 1 60 m.m., m 
173-6° F. (78-4° C.). . 
Alcohol, when acted upon by acids, furnishes by 
double decomposition a series of ethers which may 
be regarded as salts of a compound hydrocarbon 
radicle of which alcohol is itself the hydrate, 
