30 ARTIFICIAL TAN. 



though they precipitated the metallic folutions, did not affeci 

 gelaten ; but poffibly might have done fo, if the procefs had 

 been more frequently repeated, 

 —nor that of K. Sarcocol alfo produced limilar refults. 



farcocol, L. Gum Arabic afforded oxalic acid but no tan. 



Jj"bic, ^^« Tragacanth yielded much of faclatic acid, of oxalic, 



—nor of traga- ai^d of malic acid, but not the leafl; tan. 



—no/of manna. ^' ^^anna gave oxalic acid, part of which fublimed in 

 the neck of the veflTel. 



Its reliduiim formed a brown folution, which produced pre- 

 eipilates of the following colours : With fulphate of iron, a 

 pale yellow ; with muriate of tin, a pale brown ; with acetite 

 of lead, a brovvnidi white. From nitrate of lirae, oxalate of 

 lime was copioufly precipilated by it; but with ifinglafs fo- 

 lution no effec"t was produced. 

 Liquorice folu- O. Nitric folution of liquorice yielded precipitates with Tui- 

 tion precipitates pi^atg of iron and muriate of tin, after twelve hours, flight 

 brown. With acelite of lead, a brownifli red. With nitrate 

 of lead, a brown. And with gelaten, one of a yellowifii 

 brown, infoluble, and limilar to other precipitates from it by 

 tan. 

 Guiacum folu- ?• On guiacum nitric acid a6ted with great vehemence and 

 tion gave a (light fpeedily dilfolvcd it: The refiduum was almoft totally foluble 

 gdaten ^whTch in water; and this folution produced effe6ls on the metallic falts 

 wasfolublcin fimilar to ihofe recited; but with gelaten formed a flight pre- 

 wjter. cipitate, which was fpeedily dilTolved by boiling water. The 



remainder of the folution evaporated gave a large quantity oi 

 crylialized oxalic acid; fo that in this refpe6l guiacum was 

 fimilar to the gums, and anlike the refins. 



§Y. 

 Experiments on As many vegetable fubftances when roafled yield a liquor by 



feveral roafted decoaion, refembling folution of artificial tan, the author 



vegetable fub- ' " 



ftances, which tried thofe fimilarly prepared, of dried peas, horf« beans, bar- 

 donotaffeft j^^^ ^^^^ wheat flour, none of which gave any precipitate 



with gelaten. 

 Coffee gives a The decoftion of cotFee alfo gave no precipitate till after 

 precipitate with fcveral hours, and then one foluble in boiling water; but this 

 foirb'e''l'n wTe'r" '"'g'^^ ^- occafioned, the author thinks, from want of fome 



particular nicely which may be required in roafting fuch bodies 

 5 fo 



