1S2 Royal Society, London. 



nour to lay before the Royal Society, I ha\-e, "for greater 

 perspicuilv, generally conclucied with a rccapitubiMon oF the 

 contents ; but in the present case this appears to be super- 

 fluOns, as the \vhr,]e mav be concentrated into one smiple 

 fact, nameiy, that a substance very analogous to tannin, 

 which has hitherto been considererl as one of the proxiniata 

 principles of vegetables, may at any time be produced, bv 

 exposing carbonaceous subslances, whether vegetable, ani- 

 mal, or mineral, to the action of nitric acid. 



Since the preceding experiments were made, I have fur- 

 ther proved the efficacv of this substance by actual practice, 

 and have converted skin into leather by means of materials 

 which," to professional men, must appear extraordinarv, 

 such as deal saw-dust, asphailtura, common turpentine, 

 pit-coal, wax candle, and a piece of the same sort of skin. 

 Allowing, therefore, that the production of this sub- 

 Stance must for the present be principally regarded onlv as 

 a curious chemical fact not altogether unmiportant, yet, as 

 the principle on which it is founded appears to be deve- 

 loped, we may hope that a more ceconomical process will 

 be discovered, so that every tanner may be enabled to pre- 

 pare his leather even from the refuse of his present ma- 

 terials. 



The organized bodies and their products have only of 

 latfe years much attracted the attention of chemists, many 

 of whom, even at this time, (although the modes of che- 

 mical examination have been so much improved) seem dis- 

 gusted and deterred by the Proteus-like changes which 

 take place whenever these substances are subjected to ex- 

 periment. 



But these variable and end!e?s alterations of their proper- 

 ties seem rather calculated to operate as incitements to in- 

 vestitration; for by the aocumuiation of facts resulting from 

 the changes produced in these bodies by disuniting and by 

 re-combining their elementary principles, tiot only will 

 chemistry as a science become further illumined and ex- 

 tended, but it will, as it has hitherto done, render great 

 and essential services to the arts and manufactures. 



XXXVI f. Proceedivgs of Learned Societies, 



ROVAI, SOCIETY, LONDON. 



-^ HE meetings of this society commenced, after the sum- 

 Jner vacation, on Thursday, Novenober 7, the hon. Mr. 



Greville, 



