128 Mr. Hatchett’s Experiments on a Substance , 
bodies, which present an extensive surface, and also on porous 
and bibulous substances such as peat. 
But although peat, as I have already observed, does not 
contain any tannin, yet the imperfect carbonization which it 
has undergone, renders it like the roasted ligneous bodies, 
peculiarly susceptible of being converted into the artificial 
tanning substance when exposed to the action of nitric acid. 
It would be useless to enter into a detail of the different ex- 
periments which I have made upon it, as they were similar to 
those already related, and I shall Therefore only here state, 
that when seven ounces of well dried peat had been twice 
moistened, and digested with diluted nitric acid, (to the amount 
of rather more than two ounces,) and subsequently dried, I 
obtained by water a solution of the artificial tanning substance, 
which when evaporated to dryness weighed two ounces. I 
am convinced, that much more might have been obtained 
from the residuum of the peat, had I thought proper to have 
repeated the operation ; and I am also certain, that less nitric 
acid would have been sufficient, had the process been con- 
ducted in close vessels, and with other economical precautions, 
which at that time, were for the sake of expedition and con- 
venience omitted. 
§ VI. 
It has been generally stated, even by modern chemists, 
that the acids act but little, if at all, upon resinous substances. 
The contrary has however been proved, not only in the 
three Papers upon the present subject, but also in some others 
which I have formerly had the honour to lay before this 
learned Society. 
