C 10 9 3 
VI. A third Series of Experime?its on an artificial Substance , 
which possesses the principal characteristic Properties of Tannin; 
with some Remarks on Coal . By Charles Hatchett, Esq. 
F. R. S. 
Read January 1 6, 1806. 
§i- 
In my former Papers upon this subject, some account has 
been given of the effects produced by sulphuric acid upon 
turpentine, resin, and camphor ; and I shall now state the 
results of other experiments made with the same acid upon a 
great number of the resins, balsams, gum resins, and gums, 
the greater part of which, afforded that modification of the 
artificial tanning substance, which for the sake of distinction, 
I have in the preceding papers denominated the third variety. 
The process was simple digestion in sulphuric acid, after 
which, the residuum was well edulcorated, and was then 
digested in alcohol. This was separated by distillation, the 
dry substance which remained was infused in cold distilled 
water, and the portion dissolved, was examined by solution of 
isinglass, muriate of tin, acetite of lead, and sulphate of iron. 
Much sulphureous acid, carbonic acid, several of the vege- 
table acids, particularly benzoic acid, (when the balsams were 
employed, ) and apparently water, were produced during the 
operation ; but in this Paper I shall only notice two of the 
products, namely, the tanning substance and the coal. 
