SULPHURET OF ARSENICUM AS A DEPILATORY. 
75 
into the composition of indigo vats, and forms one of the constitu- 
ents of depilatory powders and paste. This is the yellow arsenic or 
false orpiment 5 which is prepared in Germany by subliming arsenious 
acid with sulphur. It contains 94 per cent, of arsenious acid, and 
only six per cent, of sulphuret of arsenic. It is almost as poisonous 
as the arsenious acid itself. The annual importation of these two 
sulphurets into France, exceeds 660,000 pounds weight. 
In the dressing of skins, the use of orpin has only been intro 
duced during the last twenty years. It causes the wool to be de- 
tached from the skin, without plunging it into a bath of lime, as was 
the practice formerly, and in this respect it has been found very ser- 
viceable. 
Having had occasion to direct my attention to some applications 
of chemistry to the art of tanning, and to substitute soda for lime in 
that process. I was also led to enquire into the use of orpin. It 
has appeared to me, for some time past, that this subject involved 
an important consideration in a sanitary point of view. 
The poisonous properties of sulphuret of arsenic, the facility with 
which it has been obtained by retail consumers, the great quantity 
of it which, in Paris, has been daily poured into the river Bievre, 
are circumstances calculated to create serious inquietude. Indeed, 
I have lately heard from M. Bussy, that in 1846, whilst making 
some experiments relating to a Report to a Commission of Health, 
he had obtained arsenical stains by Marsh's apparatus, from the mud 
procured from the bottom of the river Bievre, and also that of the 
Seine, taken from beneath the bridge of Austerlitz. It is much to 
be desired that the sulphuret of arsenic could be replaced, as a de- 
pilatory, by some other less dangerous agent. 
Hitherto the depilatory processes had not been submitted to any 
scientific investigation ; and if, according to Berzelius, we ought to 
attribute the effects of the mixture of lime and sulphuret of arsenic 
to the solubility of the skins in caustic alkali, this question, upon 
which doubt is thrown by this illustrious Chemist, leaves unex- 
plained (he preference given to the above mixture over the use of 
lime alone. 
I had, therefore, to ascertain which was really the depilatory 
agent, and whether the arsenic performed an important part in the 
process. 
In order to solve this problem, I examined separately the proper- 
