ON CATECHU. 
165 
it completely dissolves in hot water, from which, upon cool- 
ing, no inconsiderable portion of catechine is deposited from 
the thin turbid liquor. 240 parts of this Catechu treated 
with rectified alcohol by displacement, yields upon evapo- 
ration, 220 parts of extract, of which 96 per cent is soluble 
in water. The marc after displacement with alcohol, dried 
and treated with water, furnished 10 parts extract. Sul- 
phuric ether takes up 35 per cent, of soluble matter, form- 
ing with it a beautiful deep red tincture : the insoluble por- 
tion is black, tough and elastic. 
From a comparison of the above descriptive analysis, 
with the article of Gambir Catechu mentioned in the U. S. 
Dispensatory, p. 194, as also Pereira's Materia Medica, vol. 
2d, they will be perceived to be identical. Though supposed 
to be an inferior quality of an officinal Catechu, ranged 
under the head of Catechu in quadrangular cakes, a ma- 
terial difference will be perceived to exist in the character 
of the two varieties. Gambir, is preferred in the arts, not 
merely from its low price, but according to the representa- 
tion of dyers, as being richer in the astringent principle. Ex- 
periments upon it prove the proportion of tannin to be large, 
consisting chiefly of this, with apotheme, or the peculiar ex- 
tractive and catechine. From the difficulty of separating 
the compound of tannin and gelatine, a method given by 
Berzelius, to appreciate the quantity of tannin contained in 
Catechu, was resorted to. It is this : 
"Dissolve out with water the soluble matter of catechu, 
filter and add sulphuric acid, which occasions a slight pre- 
cipitate, which you separate by filtration : afterwards pour 
into the clear solution concentrated sulphuric acid, until it 
no longer precipitates. Gather the precipitate upon a 
strainer, wash with sulphuric acid diluted to about the de- 
gree of the filtered liquid, and place the strainer between 
bibulous paper to extract the moisture. Then dissolve in 
boiling water, and suffer the solution to cool. A compound 
of sulphuric acid and apotheme is deposited; filter and mix 
15* 
