426 Dr. Stenhouse on some Astringent Substances. 
II. 0°3052 gave 0°5505 carbonic acid and 0°1012 water. 
1% Il. Calculated. 
C 50°12 4.9°S7 7C =49°89 
H.. 3°72 3°71 3H= 3°49 
O 46°16 46°42 5 O = 46°62 
100:00 100°00 * -100:00 
In order to determine the atomic weight of the acid, I 
formed the bibasic gallate of lead. 
I. 0°706 of this salt gave 0°3325 lead, and 0°1802 oxide = 
76°25 per cent. oxide of lead. 
II. 0:887 salt gave 0°315 lead and 0°340 oxide of lead = 
76°58 per cent oxide. 
Now the bibasic gallate of lead C’ H O*? + 2 P bo contains 
76°69 per cent oxide of lead; there can, therefore, be no doubt 
that it was the salt analysed, and that gallic acid occurs to a 
considerable extent ready formed in divi-divi. 
Sulphuric acid throws down a very scanty dark brown pre-~ 
cipitate, even in highly concentrated solutions of divi-divi. 
When dried and distilled, it did not yield any trace of pyro- 
gallic acid, and left a very bulky charcoal, ‘The tannin of 
divi-divi appears, therefore, essentially different from that of 
nut-galls. 
Mr. Harvey informs me that a few years ago some calico- 
printers endeavoured to employ divi-divi as a substitute for 
galls, but the large quantity of mucilage it contained rendered 
it unfit for this purpose. 
It is at present pretty extensively employed in the tanning 
of leather, as the quantity of tannin it contains is considerable, 
and the presence of mucilage is not injurious to that process. 
Gum Kino.—The species of kino which I examined was the 
African variety. Iwas unable to detect in it any trace of 
gallic acid. Sulphuric acid threw down the tannin of kino as 
a bulky dark red precipitate. When distilled, it gave scarcely 
any volatile products, and no trace of pyrogallic acid. When 
digested with nitric acid, gum kino was wholly converted into 
oxalic acid. 
Catechu.—It was the light-coloured cubical variety of ca- 
techu that I employed. It does not contain any gallic acid, 
but catechin and a variety of tannin which gives olive green 
precipitates with salts of iron. Sulphuric acid throws down 
the tannin of a brownish yellow colour. When boiled with 
dilute sulphuric acid, it becomes dark brown. Like the tannin 
of oak bark, it is insoluble either in cold or boiling water. 
When boiled in strong alkaline solutions, it only dissolves to 
a very small extent. It is also insoluble in alcohol and eether. 
