2S 



Jt produces tan- 

 ning matter. 



Almoft all vege- 

 t.tble bodies yield 

 tanning matter, 

 when (ubjedled 

 to repeated ditiil- 

 lations ^^itll 

 yjitrit acid. 



Refin yields it 

 by this ticaC- 

 inent. 



As do llkewife 

 ftick lac, 



"—and balfam of 



ARTIFICIAL TAN. 



brown ; and with acetlte of lead a beautiful deep leraon^ 

 coloured precipitate, which may probably prove ufeful as ^ 

 pigiiicnt. 



Ammonia rendered the colour much deeper, and with it 

 (lepofited a large quantity of fine yellow fpiculated cryftals, 

 which did not precipitate lime from its folutions. Their 

 flavour was very bitter. 



Lallly, when this folution was added to diflblved ifinglafs, 

 it became turbid, and depofited a tough elaftic infoluble film, 

 and poflelfed the charaders of gelaten combined with tanning 

 matter. 



By this experiment the poflibility of producing tanning mat* 

 ler from bodies not converted into coal was fully afcertained; 

 and the author has fince difcovered that though indigo yields 

 ■ this matter more readily than mofi: other vegetable bodies, yet 

 almoft all produce it when fubjeded to repeated difiillations 

 will) nitric acid. 



A. The common refin did not produce the tanning fubfl.ance 

 with nitric aeid, but by the aid of fulphuric acid, as before 

 related ; yet upon this nitric acid being repeatedly abftradied 

 from it, its folution in water formed a lough yellow infoluble 

 precipitate with diffolved gelaten, fimilar to that by folution of 

 indigo, and with other re-agents produce4 the following ef- 

 fects. 



With fulphate of iron, after J 2 hours, it produced a (light 

 yellow precipitate. With nitrate of lime no effedl. With 

 muriate of tin, after 12 hours, a pale brown precipitate. An4 

 with acetite of lead a very abundant precipitate of ayeliowifl) 

 while colour. 



On repeating this experiment, the author remarked that 

 during each diftillalion nitrous gas was produced, while th^ 

 acid which came over was weakened, which made the caufe 

 of the change in the properties of the refin evident. The fol- 

 lowing are the refalts of experiments tried with other refinous 

 fubftances. 



B. Stick lac, treated as defcribed, copioufly precipitate4 

 gelaten. 



C. Balfam of Peru during the procefs afl"orded fome ben- 

 zoic acicli and gelaten was precipitated by the aquep^s folur 



