OF PALLADIUM AND PLATINUM. 
299 
The material which is dissolved off from this black powder is by no means a pure 
sulphate of platinum. It contains also bichloride, the decomposition of which appears 
to have a definite limit regarding sulphuric acid. 
Action of Ammonia on Biniodide of Platinum. 
When the biniodide of platinum is digested in water of ammonia, either cold or hot, 
it becomes gradually changed to a bright cinnabar red powder, which is insoluble in 
water. This powder may also be formed by adding water of ammonia to a solution 
of the double iodide of platinum and potassium. The liquor becomes nearly colour- 
less, and the red substance precipitates. 
On heating this body it gives off ammonia with fumes of iodine and of hydriodate 
of ammonia : water also separates. It may, however, be exposed to a temperature of 
350° Fahr. without losing water, which does not escape until complete decomposition 
has commenced. 
The analysis of this body was effected as follows : — 
32-490 grains were fused with carbonate of soda, and the residual mass digested in 
water. The platinum which remained behind weighed 12-472, or 38*01 per cent. 
The alkaline solution being rendered acid by acetic acid, was decomposed by nitrate 
of silver. The iodide of silver, being collected, dried and weighed, was 29’295 grains, 
or 89‘8 per cent., containing 48-37 of iodine. 
47'226 grains, ignited with oxide of copper in the manner already described, gave 
9*215 cubic inches of dry nitrogen, equivalent to 6*26 per cent, in weight. 
44-468 grains, ignited with oxide of copper, gave 4*584 of water, equivalent to 1*15 
of hydrogen per cent. 
These results lead directly to the formula Pt I N H 4 0 2 . or Pt 0 2 + N H 4 . 1 ., for 
which the numbers are 
Theory. 
Pt = 98-8 38*12 
Experiment. 
38-01 
0 2 = 160 
6-17 
6-21 
N = 14-0 
5-44 
6-26 
o 
11 
E 
T54 
115 
I = 1263 
48*73 
48-37 
259-1 
100-00 
100-00 
The hydrogen being found below the quantity assigned by theory, I endeavoured 
to ascertain whether a portion of it could be eliminated as water, and I exposed a 
quantity of the substance to a current of dry air at 300° Fahr. until all traces of water 
ceased to pass. The quantity of water which escaped was T95 per cent. If this were 
not hygrometric, the formula of the dry substance should be Pt I 2 + Pt 0 2 -f- 2 . N H 5 . 
and the hydrogen should be 1*20 per cent., nearly what was furnished by analysis. 
The specimen analysed for hydrogen was probably so dried. 
2 q 2 
