218 Mr. Hatchett on an artificial tanning Substance. 
vestige of tanning matter could be discovered, and the pre- 
dominant substance appeared to be oxalic acid. 
2. Another piece of Bovey coal, which had less of the cha- 
racters of wood, and was more perfectly carbonized, was 
treated in the way which has been described ; the solution was 
brown, and, unlike the former, afforded a considerable preci- 
pitate with gelatine. 
3. A portion of 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 tanning 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 similar 
result. 
6. Some deal saw-dust was digested with the nitric acid until 
it was completely dissolved ; by evaporation a yellow viscid 
mass was obtained, the solution of which in water afforded 
results like those of the first experiment on the Bovey coal, 
for oxalic acid was found in it, but not any of the tanning 
substance. 
7. Another portion of the same deal saw-dust was converted 
into charcoal in a close vessel ; the charcoal was then treated 
in the manner already described, and was thereby formed into 
a liquid which copiously precipitated gelatine. 
8. Having previously ascertained that teak wood does not 
contain gallic acid nor tannin, I reduced some of it into char- 
coal, which was afterwards readily converted into the substance 
above mentioned. 
