CHEMICAL PRINCIPLES. 
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cur-y M uh a neutral solution of the muriate of the oxide of OxiiUs of pla- 
platina, and I changed the solution as often as the intensity of *'''**' 
its colour diminished. When a fresh solution, after being 
boiled during several hours with the metallic precipitate 
produced by the mercury, suffered no change of colour ; I then 
dccaiAed it and washed well the powdry precipitate, after 
which I dried it in a heat above that of boiling water. It 
weighed 10,885 grammes. Exposed to heat in a weighed 
retort it gave mercury (but whiclt in spite of all possible edul- 
coration contained traces of the muriate of mercury). It gave 
no water. The platiua had by this means lost 2,334 gr. of its 
weight, of which 1 found 2,32 gr. in the fluid mercury. 
Fearing that the residue in the retort might not be deprived of 
all its mercury, I put it in a crucible of plalina, and heated it 
by a very strong fire. Its weight was diminished from 8,551 to 
8,51 1, and after that it lost no more weight by successive ex- 
posures to heat. It follows then that 2,374 gr. of mercury 
had contributed nothing to the reduction of the platina ; that 
is to say, that the 8,511 gr. of platina had been reduced by 
17,626 gr. of mercury; whence it appears that the plntinic 
oxide must be composed as follows : 
Platina 85, 93 100,000 
Oxygen 14,07 16,38 
• Thus we see that platina combines with exactly twice as 
much oxygen in the oxide as in the oxidule, for the small 
difference of l6,38 and 16,57 can only be attributed to the 
imperfection of the method of analysis. 
It is more ditficult than is generally imagined to procure 
the platinic oxide pure. I have made many experiments 
thereon, the results of which will be found in my Manual of 
Chemistry. (Larbok v. Kemien,)~p. 422, and p. 42Q, &c. 
When we endeavour to precipitate the platinic oxide, we 
obtain, for the most part, either a double subsalt, or else a 
combination of the precipitating substance with the platinic 
oxide. 
Oti examining the precipitate produced by the hydrosulphate 
of ammonia in a solution of the muriate of platina, I found 
that this precipitate differs according to the quantity of sul- 
phuret 
