16 llxperimeiiis on a Sulstaiicc, \*fc. 



stance, was Repeatedly treated with water until the whole of 

 this last was extracted. The bark was then again slighilv 

 roasted, was again moistened with nitric acid, and was 

 gently heated and dried as before. Water being poured on 

 it and digested, formed a brovvu solution, which copiously 

 precipitated gelatine. 



6. The whole of the artificial tanning substance was ex- 

 tracted by different portions of water, and the remainder of 

 the bark thus exhausted, was again treated in the manner 

 above described, and again afforded a considerable quantity 

 of the tanning substance, so that these processes evidentlv 

 might have been continued until the whole of the bark had 

 been converted into it. 



This might also have been accomplished, if in the first' 

 instance the exhausted bark had been converted into char- 

 coal, and digested in nitric acid, as described in nly first 

 paper; but then, the eft'ccts would have been more slowly 

 produced, and much more nitric acid would have been con- 

 sumed. I am now therefore fully coi^vinced, not only by 

 the results of the experiments related in this paper, but also 

 by many others which it would have been superfluous to 

 have slated, that the most, speedy and most ceconomical of 

 all the processes which I have described, is that of treating 

 roasted vegetable substances in the way whjch has been 

 mentioned ; and considering that all refuse vegetable matter 

 may be thus converted into a tanning substance by means 

 the most simple, and without any expensive apparatus, 

 1 cannot help entertaining nmch hope, that eventually 

 this discovery will be productive of some real public ad- 

 vantage. 



TTo be continued.] 



XII. Eepori 



