234 
NOTE UPON TANNIN. 
liquid, which contains in solution the coloring mattersof these 
same nut galls." 
This theory is based essentially, as is seen, upon the pre- 
sumption that the tannin is much more soluble in water, than 
the coloring matter of the nut galls, and subsidiary upon these 
two facts, viz.: that the tannin is the predominant principle of 
nut galls, and that it is always in excess with reference to the 
quantity of water with which it is brought in contact. 
I am persuaded that this is not the case, and that the separa- 
tion of the tannin from the other principles which is so exact 
and so complete, is solely due to the property possessed by 
this substance of combining with determined quantities of 
water and ether. In fact, by refusing to admit this new 
theory, we will be reduced to the necessity of saying, that 
we cannot separate the tannin from the aqueous solution of 
nut galls, but when this body is less soluble in water than 
the coloring matter. The elimination of the tannin is cer- 
tainly not due any longer to the preponderance of this same 
tannin, for we know that the hydrated ether abstracts from 
nut galls the least proportion of tannin that it contains, and 
at this point of the operation it is very evident that the color- 
ing matter predominates. 
Liquid tannin is approximatively formed of 
Tannin, 40 
' Water, 7 
Sulphuric ether, 53 
Total, 100 parts. 
Shaken with a mixture of ether and water, the tannin pro- 
duces a liquid, the composition of which is analogous to the 
above, although the tannin should be in contact with an excess 
of ether and water. 
The ingenious method of M. Pelouze to obtain tannin is 
certainly the best, relatively to the purity of the product, but 
it leaves much to be desired in am nyrespects. 
