124, Mr. Hatchett’s Experiments on a Substance , 
2 . 
200 grains of the same sort of bark were slightly roasted, 
and afterwards digested in water; a much darker coloured 
liquor was obtained than in the former case ; but although it 
afforded precipitates by the addition of muriate of tin, acetite 
of lead, and sulphate of iron, yet not the smallest effect was 
produced by solution of isinglass. 
3 - 
The residuum, with the remaining part of the above men- 
tioned liquor, was then digested with a small portion of nitric 
acid ; this was completely evaporated, and a brown solution 
was formed by water, which abundantly precipitated gelatine, 
4 - 
One ounce of oak bark, reduced into very small fragments, 
was repeatedly digested in different portions of water until 
the whole of its tannin was extracted. The residuum or ex- 
hausted bark (as it is called by the tanners) was dried, and 
was afterwards moderately roasted. It was then moistened 
with diluted nitric acid, which was evaporated in a heat not 
much exceeding 300° until the bark was become perfectly 
dry. This was digested in water, and speedily formed a 
yellowish-brown liquor, which abundantly precipitated gelatine. 
5 ‘ 
The bark, which after being exhausted of its natural tannin, 
had thus afforded the artificial tanning substance, was repeat- 
edly treated with water until the whole of this last was ex- 
tracted. The bark was then again slightly roasted, was again 
