ARTIFICIAL TAN, 27 



G. Fifty grains of this fubftance were dilTolved in four 

 ounces of water and precipitated by ifinglal's folution ; eighty- 

 one grains of which became thus combined with forty-fix of 

 the new tan. The remaining portion was not precipitated, 

 and was therefore feparated on a filter and evaporated to dry- 

 nefs. It was a light brittle fubftance of a pale cinnamon 

 colour, which, though com pofed of inodorous fubflances, had 

 however a firong fmell itfelf of oak bark ; which is remarked 

 as a fingular circiimftance ; and this fmell became ftronger 

 when the fubftance was put into water, in which it infiantJ^' 

 diirolved. 



The folution was very bitter ; a£led but flightly on ditfolved 

 ifinglafs ; produced a brown precipitate with fuiphate of iron, 

 and with muriate of tin a black one; had no effett with ni- 

 trate of Jime ; but with acetite of lime gave a copious preci- 

 pitate, of a pale brown colour. This fubftance appeared to 

 be the tanning mailer in the flate of extradi. 



§ IV. 



Several unfuccefsful attempts were made to form the tan- Attempts to 

 Ti'ws matter by oxi-muriatic acid. It therefore appeared, that ^"'"'^ banning 



II ■ /■ • 111 1 II 1 ^-v- r r 1 JTialter hv oxi- 



though a variety of it could be pronuced by the action or lul- muriatic" acid 



phuric acid on refinous fubflances, yet nitric acid was the mofl unfuccefsful. 



effective agent. 



The author fufpefling that the new tan might be formed Artificial tan. It 



from bodies not abfolulely converted into coal, and not being '^*^"/P^'^^'^' . 



, . n n I , r ' might be formed 



able to get any touch-wood, which he nrft thought or trying from fubflances 



for this purpofe, made the following experiment with indigo, "°' '^^2"^<^* 



which he knew to contain much carbon. 



One hundred grains of indigo, with one ounce of nitric Experiments on 

 acid diluted with a double quantity of water, was (when the j|J^i|^° ^'^^ ^^'' 

 efFervefcence had fubfided), placed in a fand-balh for feveral 

 days till evaporated to drynefs. 



The refiduura, of an orange colour, was In great part dif- 

 folved by three ounces of ditiilled water poured on it, and 

 gave a folution of a deep yellow, and intenfely bitter ; which, 

 with the fuiphate of iron, depofited a flight pale-yellow pre- 

 cipitate, and with nitrate of lime, a fmall white precipitate, 

 having the chara6ler of oxalate of lime : With muriate of tin 

 a copious white precipitate, that changed to a yellowifli- 

 • • brown ; 



