1 7G On an artificial tanning Suhstanc^. 



Having thus by means of nitric acid obtained solutions 

 from asphaltum, from jet, from several of the pit-coals, and 

 from charcoal, I evaporated them to dryness in separate 

 •vessels, taking care in the latter part of the process to eva- 

 porate very graduallv, so as completely to expel the re- 

 mainder of the acid without burning the residuum ; this, in 

 everv case, proved to be a brown glossy substance, which 

 txhibited a resinou^ fracture. 



The chenncal properties of these residua were as followy. 



1. They were speedily dissolved by cold water and by 

 alcohol. 



2. Their flavour was highly astringent. 



3. Exposed to heat, they smoked but little, swelled much, 

 and afibrded a bulky coal. 



4. Their solutions in water reddened litmus-paper. 



5. The same solutions copiously precipitated the metallic 

 salts, especially muriate of tin, acetite of lead, and o.xysul- 

 phateofiron. The colour of these precipitates was com- 

 uionlv brown, inclining to that of chocolate, excepting the 

 tin, which was blackish-gray. 



6. They precipitated gold from its solution, in the me- 

 tallic state. 



7.. They also precipitated the earthy salts, such as the 

 nitrates of lime, barytes, &c. &c. 



8. The fixed alkalis, as well as ammonia, when first added 

 to those solutions, onlv deepened the colour, hut after some 

 hours rendered them turbid. 



y. Glue or isinglass was immediately precipitated by these 

 solutions from water, and the precipitates were more or less 

 brown accordino; to the strength of the solutions. The pre- 

 cipitates were also insoluble in cold and in boiling water, so 

 that in their essential properties thev proved similar to those 

 forn^d by the varieties of tannin hitherto known, with the 

 dit^ercnce, that this factitious substance appeared to be ex- 

 empt Iron) gallic acid and mucilage, which commonly 

 accompany the varieiics of tannin, itnd which occasion 

 modifications ni the colour and appearance of soine of their 

 precipftates. 



Having thus had the satisfaction to discover that a pro- 

 duct reseniblin*!; taun.in could be formed by such a simple 

 method, not only from vegetable, but also from mineral 

 coal, I was induced to exaniine how far the same might be 

 extended to animal coal, and 1 therefore reduced a portion 



Che!Tuc:il Annals, iVRfi; by Mr. I.owitz (CreH's Chemical J'.>".'\ al. trans- 

 laied iuto English, vol. ii. p. 2.'i5.) ■ and by ^1r. Jameson, in ir- UULliuo of 

 ihe M^icralogy o£ the Sheiliind Islands, iic. Svo. edit. p. !o7. 



of 



