3 Sept. 8, 187¢] 
NATURE 
387 
know, was defended from cold by a thick coat of hair and wool. 
We find its remains embedded in peat-bogs and marshes, where 
they were mired and suffocated, and it is even claimed that here, 
as in Europe, it was contemporaneous with man. 
SCIENTIFIC SERIALS 
Annales de Chimie et de Physique, July, 1870.—This number 
Contains a paper, by M. A. Miintz, on the Composition of 
Skin, the modifications it undergoes during the process of 
tanning, and on the decomposition of tannin in the tan-pits. 
The experiments detailed in this paper were undertaken by the 
author to determine, from a theoretical point of view, the changes 
taking place in the conversion of hides into leather. A piece of 
ox-hide which was being converted into leather for the soles of 
boots was selected as the most appropriate for the investigation, 
and the operations were commenced after cleansing and de- 
pilation. In these processes no chemical change would take 
place, except perhaps in cases in which lime is employed in the 
depilation, a small quantity of which is deposited in the skin, 
but afterwards removed by a solution of glucose. The following 
process of swe//ing consists in steeping the hides in an acid liquid 
for a time varying from three weeks to twoor three months. This 
acid liquid contains acetic and lactic acids and a small quantity of 
tannin : its effect is to distend the pores of the epidermis and thus 
facilitate the subsequent process of tanning. During the swelling 
so much water and other substances are absorbed that the hide in- 
creases in weight to such an extent that it is now as heavy as it 
was before the cleaning and depilation, the addition of dry 
matter amounting to nearly 19 per cent.; asmall quantity of 
mineral matter is lost, the augmentation being due to the ad- 
dition of carbon, hydrogen, and oxygen. After eleven months 
in the tan-pit an increase of nearly 83 per cent. was ob- 
served ; a small diminution in the quantity of nitrogen took 
place, while the mineral constituents and carbon, hydrogen, and 
oxygen were augmented. The organic materials added had 
exactly the same composition as those absorbed by the hide 
during swelling, but they differ much from the composition of 
tannin. The author believes that the loss of nitrogen during 
the tanning process is due to a decomposition of part of the 
leather, for ammonium salts were found in the liquor from the 
tan-pits. The structure of leather is also very different from that 
of skin; while the latter is fibrous the former is spongy ; 
skin will absorb three or four times its weight of water, swelling 
considerably, but leather scarcely absorbs one and a half 
times its weight, and without increase of volume ; 100 parts of 
skin by treatment with boiling water leave 3°35 of insoluble 
matter, the rest being converted into gelatine; the residue from 
_ leather under the same circumstances is about 48 per cent. The 
compound obtained by the action of tannic acid on gelatine differs 
very much in composition and properties from leather. <A 
description is given of a process for the estimation of tannic 
acid; and M. Miintz announces the observation that the residue, 
after boiling skins with water, contains a substance dissolved by 
Schweitzer’s cupro-ammoniacal reagent, and thus resembling 
cellulose, but containing about 15 per cent. of nitrogen. 
The author next gives an account of the composition of the 
mineral substances present in skin and in leathes, and points out 
the changes produced during the tanning. He concludes that the 
tannic acid is partially converted into more oxidised compounds, as 
gallic acid, glucose, lactic, acetic, formic, carbonic acids, and most 
probably propionic acid, the remaining less oxidised residue 
converting the skins into leather. The experiments detailed in 
this paper were carried out in the laboratory of M. Bossingauult. 
—M. L. Henry contributes a paper on glyceric tribromhydrine, 
the object of which is to show that the compound obtained by 
Berthelot by the action of phosphoric bromide on dibromhydrine 
or epibromhydrine, and described by him as tribromhydrine, 
must haye been some other compound, The author points out 
that the saturated compounds of the triatemic radical (C,H,),”” 
obtained either from the allylic group or from glycerine, are 
always identical, with the single exception of Berthelot’s tribrom- 
hydrine, which boils at 180°, while the tribromide of allyl 
obtained by Wurtz by the action of bromine on allylic iodide, 
boils at 217—218°. He also shows that the analysis given by 
Berthelot is not as concordant with the theoretical numbers 
as might be expected, and that the physical properties described 
by him do not correspond with those that might be looked for 
in a compound of the composition C, H; Brg. Finally, he an- 
nounces that by the action of phosphoric bromide on pure 
dibromhydrine, he has obtained the true tribromhydrine, which, 
in all its physical and chemical properties, is identical with the 
tribromide of allyl of Wurtz.—The next paper is by M. P. 
Schiitzenberger, on a new acid of sulphur. Schénbein ob- 
served that when a solution of sulphurous acid is placed 
in contact with zinc the liquid becomes yellow, and ac- 
quires the property of decolorising indigo and litmus, but 
after a short time sulphur is deposited and the reducing 
action of the liquid disappears. M. Schiitzenberger has em- 
ployed a concentrated solution of sodic bisulphite in the place of 
the sulphurous acid, and has succeeded in preparing the salt of 
a new acid. A flask of about half a litre capacity was filled 
with zinc shayings and a strong solution of sodic bisulphite 
poured in, The vessel was then closed and placed in cold water ; 
after half an hour the odour of sulphurous acid had disappeared, 
when the liquid was poured into a flask containing 14 litres of 
alcohol and the mixture agitated. A crystalline deposit of the 
double sulphite of sodium and sodium was produced, and from 
this the clear liquid was rapidly decanted into bottles, which 
were filled entirely, closed, and allowed to cool. After a short 
time a mass of fine colourless needles was deposited, consisting 
of sadic hydrosulphite (SO HY O + H,0. It is rapidly'oxi- 
dised by exposure to the air into sodic bisulphite, and the solu- 
tion when placed on filter paper is so rapidly oxidised that 
sufficient heat is evolved to cause steam to be given off. On 
adding sulphuric or oxalic acid to the solution an orange 
red colour is produced, but the liquid is rapidly decolorised 
with deposition of sulphur. Sodic hydrosulphite may also he 
obtained by nascent hydrogen evolved by electrolysis. The 
production of this compound is represented as follows :— 
COl}o.+m, = SQA I0 + n0, 
_Sodic Sodic rt 
bisulphite hydrosulphite 
The oxidation of the hydrosulphite thus :— 
(SO Hy’ : & (SO} 
Na) $0'+ 0 = NOS O.. 
The decomposition of the acid :— 
SO Hy) 
ata "Yo = 2H,O + S + SO,. 
The solution of the sodium salt is gradually transformed, out of 
contact with air, into sodic hyposulphite and water :— 
SO Hy 
ait we $0 a 
Sodic 
hydrosulphite 
H,O + S,0,Na,. 
Sodic 
hyposulphite 
By means of an alkaline solution of sodic hydrosulphite indigo 
is rapidly converted into white indigo ; acetone produces isopro- 
pylic alcohol; and oil of bitter almonds is partially transformed 
into benzylic alcohol. This substance promises to be a useful 
reducing agent for many operations. 
In the Revue des Cours Scientifigus for Aug. 27 is a transla- 
tion of Prof. Hofmann’s address in honour of the late Prof, 
Graham, delivered before the German Chemical Society, which 
occupies the greater part of the paper. Then follows a report of 
the sittings of the Anthropological Society of Paris on April 21 
and May 5, containing a report on the Ethnology of Lower 
Brittany, which led to an animated discussion on the origin of 
species and the theories of transformation and natural selection. 
A translation is also given of Prof. Sterry Hunt’s paper, read 
before our Royal Society, on the probable seat of volcanic 
action. Inthe number for September 3 is a report from M. 
Giraud-Teulon on the causes of myopy, its relative frequency, 
and its influence in military efficiency. M. Marey continues his 
interesting and valuable paper on the flight of birds, which is 
here discussed from a mechanical point of view. We have the 
reports of the sittings of the Anthropological Society on May 
19, June 2 and 16, and July 7 and 21; the subjects of discussion 
being the brain of man and of the primates, pathological oste- 
ology of the newly-born, acclimatisation of Europeans in Africa, 
and the conclusion of the discussion on transformation. The 
variédlés comprises a paper by Prof. Nélaton, of the Faculty of 
Medicine of Paris, on wounds produced by fire-arms, 
