on the constituent Parts of astringent V egetables . 259 
even in their pure states ; and, for the purposes of commerce, 
they are often adulterated to a considerable extent, with sand, 
and earthy matter * 
In attempting to estimate the composition of the purest cate- 
chu, I selected pieces from different specimens, with which I 
was supplied by the President, and reduced them together into 
powder ; mixing, however, only those pieces which were from 
catechu of the same kind. 
Two hundred grains of the powder procured in this way, 
from the catechu of Bombay, afforded by analysis. 
Grains. 
Tannin - - - - - 109 
Peculiar extractive matter - - 68 
Mucilage - - - - 13 
Residual matter; chiefly sand and calcareous earth 10 
The powder of the Bengal catechu gave, by similar methods 
of analysis, in 200 grains, 
Grains. 
Tannin - 97 
Peculiar extractive matter - - ”73 
Mucilage - - - - 16 
Residual matter; sand, with a small quantity of calca- 
reous and aluminous earths - - -14 
In examining those parts of the catechu from Bengal which 
were differently coloured, I found the largest proportion of 
tannin in the darkest part of the substance ; and most extractive 
matter in the lightest part. It is probable that the inequality of 
composition in this catechu, is owing to its being evaporated 
• One specimen that I examined, of the terra japonica of commerce, furnished, by 
incineration, j of sand and earthy matter ; and another specimen, nearly J. 
LI 2 
