178 On an artificial tanning Sulstance. 



2. Another piect; of Bovey coal, which had less of the 

 characters ot wood, and was more purt'eclly carbonized, was 

 treated in the wav which has been described ; the solution 

 was brown, and, unlike the tornier^ afforded a considerable 

 precipitate with gelatine. 



3. A portion ot" the first sort of Bovey coal was exposed 

 to a red heat in a close vessel, and was then reduced to 

 powder and digested with nitric acid ; here a remarkable 

 difference was to be observed, for nearly the whole was thus 

 converted into the taiining substance. 



4. A coal from Sussex, extremely like the second sort of 

 Bovey coal, also afforded the same product. 



5. A piece of the Surturbrand from Iceland yielded a si- 

 miUr result. 



6. Some deal saw-dust was digested with the nitric acid 

 until it was completclv dissolved ; by evaporation a yellow 

 viscid mass was obtained, the solution of which in water 

 afibrded results like those of the first experiment on the 

 Bovey coal, for oxaJic acid was found in it, but not any of 

 the tanning substan^. 



7. Anotlier portion of the same deal saw-dust was con- 

 verted into charcoal in a close vessel ; the charcoal was then 

 treated irv the manner already described, and was thereby 

 formed into a liquid which copiously precipitated gelatine. 



S. Having previously ascertained that teak wood does 

 not contain gallic acid nor tannin, I reduced some of it 

 into charcoal, which was afterwards readily converted into 

 the substance abovementioned. 



In these experiments, the deal and the leak wood had 

 been reduced to the state of coal, as usual, by fire ; but as 

 this does not appear to have been the means generally em- 

 ployed by nature to convert organized substances into the 

 varieties of mineral coal, I for a considerable time previous 

 to the discovery of the artificial tanning product had beea 

 employed in a series of experiments on the slow carboni- 

 zation of a great number of vegetable substances by the 

 humid way. 



The agent which I most commonly used to produce this 

 effect was sulphuric acid occasionally diluted ; and although 

 many of the processes were extremelv unplca^ant and tedi- 

 ous, yet I ha\ e not any reason to rearet the time which has 

 been thus employed. The subject, however, I foresee will 

 bianch out in|^; several details, none of which as yet I can 

 regard as suiilcientlv completed to merit the honour of 

 being submitted to this learned society ; but I am in a 

 manner almost compelled in the present case to antici,pate 



a few 



