77 
A NEW CHROMIUM GREEN. 
BY M. MATHIETT PLESSY. 
One part of bichromate of potash is dissolved in 10 parts of boiling water, 3 litres of 
biphosphate of lime, and 1 kilo. 250 grammes of brown sugar. * 
A considerable evolution of gas is produced after some time, and when the reaction is 
complete, the mixture is allowed to stand a day or two, and the green deposits. The 
precipitate is washed with cold water till all trace of acid is removed, and dried by a 
gentle heat. 
This green, which contains no poisonous ingredient, is not altered by light; sul¬ 
phuretted hydrogen does not act on it; mineral acids, even concentrated, do not 
destroy it, and dissolve it but very slowly. It has been found to give an excellent 
green paint, and may be fixed by albumen on fabrics .—Repertoire de Chimie. 
ON THE ACIDS OF GUM BENZOIN. 
BY MM. KOEBE AND LAUTEMANN. 
The peculiar acid discovered by M. Kolbe and Lautemann in the gum benzoin of 
Sumatra, and supposed to be toluylic acid, has been found by the authors to be a com¬ 
plex acid made up of two parts of benzoic and one part of cinnamic acid. It is easy 
to prove the presence of the latter. The gum resin is boiled with milk of lime, filtered, 
and the filtrate precipitated by hydrochloric acid. Permanganate of potash is then 
added. If cinnamic acid be present, the odour of bitter almonds is developed, arising 
from its reduction. 
These two acids are always found in the same proportions in the different varieties 
of benzoin. The authors thought from this fact that they existed as a conjugate acid, 
similar to the butyro-acetic, of the component acids of which they are liomologues. 
Acetic Acid C 4 H 4 0 4 Benzoic Acid C 14 H 0 O 4 
Butyric Acid C 8 U 8 0 4 Cinnamic Acid C 18 H 8 0 4 
However, the combination is not so intimate, for the acids may be separated not only 
by fractional precipitation, but by simple crystallization. The fusing-point of this 
complex acid is 26° (78° Fahr.) less than that of Benzoic acid, 120° (249° Fahr.) ; and 
Aschoff has ascertained that it requires very little cinnamic acid to lower considerably 
the fusing-point of benzoic acid. 
The complete separation of these acids was effected by fractional precipitation from 
their ammoniacal salts with nitrate of silver. 
M. Aschoff has ascertained the exclusive presence of cinnamic acid in the kernels of 
a benzoin from Sumatra, which had a strong odour of storax. The greater part of 
these kernels were soluble in ether. The solution contained,— 
Cinnamic Acid . 11 p.c. 
Resin soluble in alcohol . 78 p.c. 
Extractive matter . 4'5 p.c. 
The kernels also contained 5 - 4 p.c. of a resin soluble in alcohol but insoluble in 
ether .—Journal de Pharmacie. 
ESTIMATION OF NITRIC ACID. 
'BY M. H. BOSE. 
M. F. Reich has shown that powdered quartz drives off the nitric acid from nitrates, 
and particularly from alkaline nitrates, at a barely perceptible red heat. This reaction 
may be made available in the determination of nitric acid by difference. The nitrate 
is merely heated with four or six times its weight of quartz in fine powder. 
* We give the quantities as recommended by the author, although the proportions are 
not very evident. 
VOL. V. 
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