238 MR HENRY HOW ON CERTAIN SALTS AND 
the new acid is deposited in fine, square, prismatic crystals, often of considerable 
length, and presenting a very beautiful appearance, from their high refractive 
power. 
It may also be obtained by addition of bromine water to solution of acid 
comenate of ammonia, but I found it more convenient to employ the acid itself. 
I may mention that in one instance, when operating upon a solution of the am- 
monia salt, a considerable excess of bromine failed to yield any new acid, even 
after the lapse of many hours. The solution remaining colourless, more bromine 
was added, and as no crystals appeared, the fluid was evaporated, but still without 
any signs of bromocomenic acid; and it was not until the liquid was reduced to 
a very small bulk, that any substance crystallized out. On pouring off the liquid, 
which had now become nearly black, there were found some considerable-sized 
transparent crystals, together with a little bromocomenic acid in groups. The 
crystals became perfectly colourless on washing with a few drops of water; they 
proved to be oxalic acid. This acid always appears in the mother liquors from 
which chloro and bromo comenic acids have been separated by evaporation, result- 
ing probably from a secondary decomposition. 
The crystals, as obtained by the action of bromine water upon comenic acid, 
after being washed, and recrystallized from boiling water, gave the following 
results :— 


6-001 grains dried at 212° Fahr. gave 
6‘767 ... carbonic acid, and 
0-806 ... water. 
4-330 grains dried at 212° gave, when burned with lime, 
3-475 ... of bromide of silver. 
Experiment. Caleulation. 
aT TT 
Carbon, . : 30°75 30°63 Cris 72 
Hydrogen, > 1:49 1:27 A 3 
Oxygen, . : uae 34:06 OF 80 
Bromine, . : 34°15 34:04 Br 80 
100-00 100:00 235 
which shew that they consist of an acid precisely analogous with chlorocomenic 
acid; an equivalent of bromine taking the place of one of hydrogen in the comenic 
acid. In the hydrated state it contains, like the chlorine acid, three atoms of 
water. 
11-14 grains air-dry acid lost at 212° 
LoD) asics pawaters 
which corresponds to 10°32 per cent. ; 10°30 is the number required by the formula 
2HO C,, beat O, +3 aq. 
This acid so closely resembles the chlorocomenic in its general properties and 
products of decomposition, that a very few words will suffice to describe it. It is 
iets ctrentainten 
