on a Substance possessing the Properties of Tannin. 315 
inferior to that of the first variety, into which however ( as we 
have seen ) it may easily be converted by nitric acid. 
From the mode of its formation, there does not appear 
to be any positive evidence that it contains nitrogen like the 
first and second varieties, and perhaps the absence of nitro- 
gen may be the cause of its less powerful action ; this I have 
not as yet ascertained, but it is my intention more particularly 
to notice in a future Paper the general properties of this 
substance. 
S s a 
