REPORT ON CHEMISTRY. 
467 
few drops of chromate of potash. If any bichloride be present, 
a number of small red points of chromate of mercury are imme¬ 
diately deposited. 
Lowig * has proposed another mode. The dry mixture of 
chloride and bromide is heated in a stream of chlorine gas 
and the vapours made to pass through caustic potash, by which 
chloride of potassium and chlo rate and bro mate of potash are 
formed. A solution of nitrate of silver precipitates the chlo¬ 
rine and the bromic acid. A solution of caustic barytes digested 
on the moist precipitates takes up the bromic acid only. The 
excess of barytes is separated by carbonic acid, and the bro- 
mate of barytes obtained by evaporation ; or the barytic solu¬ 
tion may be neutralized by nitric acid, and the bromic acid 
precipitated again by nitrate of silver. 
Oxacids of cyanogen .—The nature and remarkable proper¬ 
ties of the compounds of cyanogen and oxygen have been beau¬ 
tifully cleared up in an able Memoir (Ann, de Chimie, xlvi. 
p. 25,) by MM. Wohler and Liebig. They have shown that 
the cyanic acid of Serullas contains hydrogen according to the 
formula 1^ (Cy + 2 O-f H), and have given it the name of cya- 
nuric acid. This acid distills over without loss, and condenses 
in the cooled receiver into a limpid colourless liquid, which is 
the cyanic acid of Wohler, combined with one atom of water. 
It is represented by the formula (Cy-f-O) + (H + O), in which 
the elements are precisely in the same ratio as in the cyanuric 
acid,—from which it appears that by heat the atoms constituting 
cyanuric acid are arranged so as to produce one atom and a half 
of a hydrated cyanic acid containing one atom water. But 
this new arrangement of the atoms is very unstable ; for on ac¬ 
quiring the temperature of the atmosphere it begins to grow 
turbid, evolves heat, enters into ebullition, and in a few mi¬ 
nutes is converted into a dry, compact, brilliant, white solid, of 
the same composition as the cyanuric and hydrated cyanic acids, 
and which, from its insolubility in water and nitric and muriatic 
acids, has been called insoluble cyanuric acid. 
I had drawn up a short outline of the properties and several 
modes of obtaining these acids ; but as I find Dr. Turner, in the 
fourth edition of his Chemistry , just published, has inserted all 
the most important facts, I cannot do better than refer the 
reader to that excellent work. 
Metals, precipitation of, from solutions in a malleable state. 
—It is a well-known fact, in chemical science, that certain metals 
in the metallic state introduced into the saline solutions of cer¬ 
tain others, deprive the latter of their acid and oxygen, and 
* Geiger’s Magazin, xxxiii. p. 10. 
2 G 2 
