52 M. Wohler on a new Mode of forming Subowide of Silver. 
water mutually replace each other, so that with increase of the 
potash there is decrease of the water, and vice versd. Schwar- 
zenberg’s analyses led to the formula KO, 3Co? O° + 3HO. 
This relation of cobalt to oxygen was so unusual that the co- 
baltate of potash became the subject of separate investigation 
by Pebal* and Mayer +, who have, however, arrived at results 
which confirm in the main Schwarzenberg’s statements. 
Pebal’s experiments were made chiefly with a view of deter- 
mining the relation of cobalt to oxygen in the acid, and he ac- 
complished this by the application of Bunsen’s method of volu- 
metric analysis. Pebal’s analyses, which agreed well with each 
other, gave numbers corresponding to the formula Co® 0", KO, 
or 2(Co?O*), KO. The relation of the cobalt to the oxygen 
is therefore the same as that found by Schwarzenberg; but 
Pebal does not consider that water is contained as an essential 
constituent in the substance. 
Mayer’s object was not solely to determine the relation of cobalt 
to oxygen, but also to examine whether cobaltic acid might not 
be a mixture of two oxides of cobalt, the more so as Fremy had 
stated that an oxide of cobalt, Co O?, was formed under certain 
circumstances. Mayer also investigated with great complete- 
ness the various methods of forming cobaltate of potash. His 
experiments confirm essentially Schwarzenberg’s statements, 
and his analyses agree with the formula 3(Co* 0°) KO, 3HO. 
But he does not consider that it can be called cobaltate of pot- 
ash ; it is rather a peroxide, which has the property of com- 
bining with bases; on treating it with water, the greater part 
of the potash is removed, although the relation of cobalt to 
oxygen remains constant ; many instances of this class of com- 
pounds are known, which suffer a progressive decomposition 
with water. Mayer considers that the water is an essential con- 
stituent, and he explains the difference in this respect from 
Pebal’s views as arising partly from the ready decomposibility of 
the potash compound with water, and partly from the production 
of different compounds, according as circumstances are modified. 
Wohler { describes a new mode of forming suboxide of silver. 
When yellow arsenite of silver is digested at a moderate tempe- 
rature with caustic soda, it rapidly becomes black. When this mix- 
ture is made to boil, allowed to settle, and the clear liquid poured 
off, it is found to contain arseniate of soda. The black precipitate 
is again boiled with fresh soda, then well washed out with water 
and dried. It then forms a heavy black powder, with a shade 
of grey, and under the burnisher has a metallic appearance. It 
consists of suboxide of silver containing a little metallic silver. 
* Liebig’s Annalen, December 1856. + Ibid. March 1857. 
{ Ibid. 
