COLOURING MATTERS OP MADDER. 
71 
Deducting the amount of oxide of lead, there remains, for 
the acid C 56.1, H 5.4, 38.5, which is the composition of 
carTeo-tannic acid. 
To convince myself of the identity of these two acids, I 
decomposed a portion of the lead salt which had been em- 
ployed for the above analysis with sulphuretted hydrogen. 
The solution filtered from the sulphuret of lead was slightly 
yellow, acquired a dark reddish-yellow colour with ammo- 
nia, potash or soda, and was coloured dark green with per- 
chloride of iron. Mixed with an excess of ammonia and 
exposed to the air, the liquid became dark green, which co- 
lour was converted into brown by the addition of acetic acid. 
The brown acid liquid afforded with a solution of acetate of 
lead a dark blue precipitate, which was coloured red by sul- 
phuric acid. All these reactions agree with those presented 
by carTeo-tannic acid under the same circumstances ; conse- 
quently the identity of the acid contained in the leaves of 
Ilex Paraguayensis with that existing in the berries of cof- 
fee is proved. — Ibid, from Jinn, der Chem. und Pharm. 
ART. XVII. — ON THE COLOURING MATTERS OF MADDER. 
By Dr. Schunck. 
On treating finely-ground madder roots with boiling wa- 
ter, a brown fluid is obtained having a taste between bitter 
and sweet. In order to extract all the substances capable 
of solution in water, about sixteen quarts of water are re- 
quired for every pound of madder. To this fluid any strong 
acid, such as sulphuric or muriatic acid, is added in slight 
excess. Nitric acid must not be used for the purpose. Ox- 
alic acid is best adapted, as it can afterwards be completely 
removed by chalk. The acid produces a dark brown pre- 
cipitate, which is separated by filtration, and washed with 
water until the excess of acid is removed. The percolating 
fluid is yellow. This brown precipitate consists of seven 
