TURPENTINE AS A SOLVENT TOR CAOUTCHOUC. 229 
M. electa a yellowish- white opacity, upon which after a time 
the periphery of the liquid acquires a bright violet colour, 
while the centre remains yellow. M. indica behaves simi- 
larly, only that the colour is darker ; pseudo-myrrh does not 
exhibit this reaction. Fuming nitric acid produces with the 
tincture of M. electa an umber-brown, and finally a dark 
violet colour; on evaporation a dark gamboge- coloured 
residue is left ; M. indica exhibits the same reaction ; pseudo- 
myrrh experiences no change. Bdellium indicvm and 
africanum are distinguished by their not assuming a violet 
colour on their treatment with nitric acid. About 10 grs„ 
of myrrh, shaken with an ounce of water and filtered, yield 
with solutions of salts of oxide of lead a considerable pre- 
cipitate. Bdellium indicum, treated in the same manner, 
exhibits scarcely any opacity. — Chem. Gaz.,from Archiv . 
der Pharm, 
ART. L,— ON" THE EMPLOYMENT OF ESSENCE OF TUR- 
PENTINE AS A SOLVENT FOR CAOUTCHOUC. 
By M. Bouchardat. 
About ten years since I was consulted by a manufacturer 
of waterproof fabrics, as to the best solvent for caoutchouc. 
At that time either essential oil obtained by distilling coal 
tar, or oil obtained by the open distillation of caoutchouc, 
was used in England. 
I commenced by carefully studying the nature of this 
pyrogenous oil, and separated from it several kinds of car- 
buretted hydrogen, remarkable by their point of ebullition 
being very low; I was not long, however, in being con- 
vinced, that if pyrogenous oil of caoutchouc is a good solvent 
of that substance, its cost will prevent its being for some 
