% 
J. W. Mallet on Osmious Acid. 59 
can be erystallized, nor has the constitution assigned to either 
been supported by an analysis. The so-called ammonio-sesqui- 
oxyd detonates when heated, (sometimes with much violence, as 
I have noticed in removing by heat the deposit of this substance 
which forms on the end of a retort-neck during the distillation 
of osmic acid into a receiver containing ammonia,) and hence is 
probably analogous to fulminating platinum, containing perhaps 
the binoxyd of osmium. The binoxyd itself is a feeble base, 
the characteristic color of whose salts in solution is yellow as is 
the case with the corresponding compounds of iridium. Similar 
remarks apply to the binoxyd of ruthenium—probably the body 
obtained, as we have shown, by Frémy in crystals. The teroxyd 
of osmium is the body supposed to have been isolated in the ex- 
periment described at the beginning of this paper. Its position 
apparently, than those of osmic acid, as nitrous acid is more 
t NO, or SbO does so. No so-called osmiate has 
— been analyzed; the saturating capacity of the acid, if it be 
nown. 
The tendency throughout the whole arsenic group is manifestly 
to the production of the acid compounds MO, and MO,, the for- 
‘Mer the more fusible and volatile body, the latter the stronger 
' acid. Th addition we have some cases of the rotoxyd aon 
¥ 
of 
fitle base, and the binoxyd (MO,), a body of still more fee 
‘Properties, verging upon the acids. All other grades 
