C *853 
XXI. Additional Experiments and Remarks on an artificial Sub- 
stance, which possesses the ■ principal characteristic Properties of 
Tannin. By Charles Hatchett, Esq. F. R. S. 
Read June 27, 1805, 
§i- 
W hen I had ascertained that carbonaceous substances, whether 
vegetable, animal, or mineral, were capable of being converted 
into a product, which, by its effects on earthy and metallic 
solutions, on dissolved gelatine, and on skin, resembled the 
natural vegetable principle called Tannin, I was at first inclined 
to give it the name of artificial or factitious tannin ; but some 
eminent chemists of this country, for whose opinions I have 
the highest respect, considered this name as objectionable ; for 
although the artificial substance resembles tannin in the parti- 
culars above stated, yet in one character there appears to be a 
very considerable difference, namely, the effect of nitric acid ; 
for by this, the artificial substance is produced, whilst the 
varieties of natural tannin are destroyed. Such an objection, 
sanctioned by such authority, induced me to alter the title of 
my Paper, and to expunge the word tannin wherever it had 
been applied to the artificial product. 
In order to satisfy myself more fully on this point, I have, 
since the communication of my former Paper, made a few ex- 
periments on the comparative effects produced by nitric acid 
