on a Substance possessing the Properties of Tannin. 
ounces of water, and were afterwards precipitated by dissolved 
isinglass, eighty-one grains of which became thus combined 
with forty-six grains of the tanning substance. 
The remaining portion of the latter was not precipitated, and 
was therefore separated by a filter, and evaporated to dryness. 
It then appeared in the state of a light brittle substance of a pale 
cinnamon brown colour ; and it is very singular, that although 
charcoal is an inodorous body, and although the artificial tan- 
ning substance, when properly prepared, is likewise devoid of 
smell, ( unless a certain pungent sensation which may be per- 
ceived upon first opening a bottle containing the powder after 
agitation should be so termed, but which seems rather to be a 
mechanical effect ) yet this substance possessed a strong odour 
not very unlike prepared oak bark, and this odour became much 
more perceptible when the substance was put into water, in 
which it immediately dissolved. The solution was extremely 
bitter, and acted but slightly on dissolved isinglass, with which, 
however, it formed some flocculi ; with sulphate of iron it pro- 
duced a brown precipitate ; with muriate of tin one which was 
blackish brown ; nitrate of lime had not any effect ; but acetite 
of lead occasioned a very copious precipitate of a pale brown 
colour. This substance therefore appeared to be a portion of 
the tanning matter so modified, as partly to possess the charac- 
ters of extract.* 
Other experiments were made on the tanning substance pre- 
pared from various bodies, which by the dry and by the humid 
way had been previously reduced to the state of coal ; but these 
I shall here omit, and shall pass to the description of a series of 
* When added to a solution of carbonate of ammonia, it produced some efferves- 
cence, but its peculiar vegetable odour did not suffer any diminution. 
