24 ARTIFICIAL TAN. 



Expeiiments o. Ten grains of the new tan, mixed with ten grains of 



continued. white fugar, difTolved in half an ounce of nitric acid, was 



diftilled to drynefs. The refiduum was not changed by the 



gelatinous or other re-agents. 



3. This experiment was the fame as the former, only that 

 gum arable was employed in place of fugar. The refult was 

 the fame. 



4. The precipitate from a folution of ifinglafs, with which 

 the artificial tan had been mixed, was well waflied with dif- 

 tilled water and then dried. In this ftale it was digefted in 

 flrong nitric acid, by which a dark-brown folution was 

 formed ; which was evaporated to drynefs, and the fubftance, 

 diflblved in boiling diftilled water, was examined by nitrate 

 of iron, acetite of lead, muriate of tin, and folution of ifin- 

 glafs, with all of which it threw down copious precipitates, 

 lihiilar in all refpefts to the artificial tan, which had not been 

 fubje6ted to the procefs defcribed. 



5. Some of the precipitate of ifinglafs by the new tan wa« 

 difTolved in muriatic acid, and evaporated to drynefs: of this 

 boiling diftilled water diftblved only a part ; and the folution, 

 of a dark beer colour, did not precipitate gelatine, though it 

 afted on muriate of tin and fulphate of iron ; for with the for- 

 mer it gave an afli-coloured precipitate, and with the latter a 

 flight depofit of a reddifh-brown. 



6. As boiling water difTolved only a part of the ifinglafs 

 precipitate in the former experiment, the remainder was 

 treated with nitric acid ; after which, on being evaporated 

 to drynefs, it was found to be completely foluble in water, 

 and precipitated gelatine as copioufly as at firft. 



7. Twenty grains of the new tan was difTolved in half an 

 ounce of muriatic acid : The refiduum, after evaporation to 

 drynefs, appeared in every refped unchanged. 



The author here makes the obfervation, mentioned at the 

 conclufion of the former paper, relative to the foUuions of the 

 new (an not becoming mouldy like thofe of galls, fumach, and 

 catechu, and feeming to be completely imputrefcible. 



And having thus afcertained the unchangeable nature of 

 this fubftance, he made the following comparative experi- 

 pients on galls, fumach, Pegu cutch, kafcatti, common culch, 

 ^ud oak bark, 



8, Twenty 



