972 Royal Society of London. 



tion, was converted into a vellovv viscid substance similar 

 to that obtained from the resins. Mr. Hatchett therefore 

 concluded that the dark bfown sokition was formed by the 

 action of the nitric acid on the uncombined carbon of the 

 bitumens ; that the deep yellow portion constituted the 

 essential part of the bitumens ; and therefore that the 

 dark solution was in fact dissolved coal. He accordingly 

 tried pit coal, and, by a similar treatment, obtained the 

 same dark brown solution in great abundance, but not 

 when he used coals which contained little or no bitumen. 



Having by means of nitric acid obtained solutions from 

 asphaltum, from jet, pit coals, and charcoal, he evaporated 

 each to dryness, veiA" slowly, to expel the remaining acid 

 without burning the residuun), which in each was a glossy 

 brown substance, exhibiting a resinous fracture, soluble in 

 water and in alcohol, and highly astringent. Exposed to 

 heat, they smoked but little, swelled, and yielded a bulky 

 coal. Their solutions reddened litmus paper, and precipi- 

 tated various metallic and earthy salts, and also glue or 

 isinglass, Yielding a precipitate insoluble in water, either 

 hot or cold — and consequently possessing all the properties, 

 of tannin, uncontaminated with gallic acid. 



Mr. Hatchett then reduced some animal substances to 

 the state of charcoal, and by a treatment similar to the. 

 above obtained from them tannin. 



Some kinds of coal, which in their natural state yielded 

 little or no tannin, on being brought to a red heat in a close 

 vessel, and then digested with nitric acid, were almost 

 wholly converted into that substance. The result was the 

 same with various kinds, of wood; — when charred they 

 yielded a great quantity of tannin, though before under- 

 going that process they would yield none. 



This ingenious paper contains other interesting details on 

 matters connected with this subject, all tending to show 

 that different substances yielded tannin in proportion to the 

 quantity of their original carbon, and that substances re- 

 duced into coal in the humid way (as by the action of 

 sulphuric acid) in like maner yield the tanning substance 

 by nitric acid; but we shall not enter more into this detail 

 till the paper itself be published. 



On the 4th of July was read a paper by W. Hyde Wol- 

 laston, M. D. on the discovery of palladium ; with ob- 

 servations on other substances found with platina. 



The autlior, having purified a great quantity of platina 

 by precipitation, had an opportunity of examininjj 

 the various impurities usually mixed with the ore. 



This 



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