743 
1908-9.] The Atomic Weight of Platinum. 
give a doubly high result, on account of a too small amount of silver 
chloride, as well as a too great weight for the platinum. If some of the 
potassium chloride had been driven, during the heating, into the hydro- 
chloric acid absorbers, the ratio 2AgCl : Pt would give a high value, while 
the value from the ratio 4AgCl : Pt would be correspondingly low. 
The Analysis of Ammonium Chloroplatinate and Bromoplatinate. 
The analysis of the ammonium salts was carried out in much the same 
way as in the case of the potassium salt, except that here the salt could not 
be heated to as high a temperature for the purpose of expelling the occluded 
water. The purest sample that I have been able to prepare would de- 
compose slightly above 185°. All the hydrochloric or hydrobromic acid 
seemed to be driven off below 150°. Nevertheless, as the salt might still 
contain an appreciable amount of water, the values for the atomic weight 
obtained from ratios in which the weight of original salt appears are not 
used in estimating the final mean value. On account of the low tempera- 
ture at which the ammonium chloride or bromide volatilises, and the 
consequent difficulty of preventing some of this salt from being carried 
over into the absorption bottles, with the halogen acid, it was thought 
safer to estimate the ammonium chloride or bromide, and the acid 
formed, together. The results given by these analyses, together with the 
ratios obtained, are set forth in the tables below. The atomic weight 
values for nitrogen, hydrogen, and bromine used in the calculations were 
those given above. 
Table V. — Results of the Analysis of Ammonium Chloroplatinate. 
Experi- 
ment. 
Preparation. 
Weight of 
(NH 4 ) 2 PtCl 6 
in vacuum. 
Weight of 
Platinum 
in vacuum. 
Weight of 
6AgCl 
in vacuum. 
Weight of 
6Ag 
in vacuum. 
(NH 4 ) 2 PtCl 6 . 
Silver. 
13 
I. 
II. 
1 -75088 
0-76976 
3-39181 
2-55181 
14 
55 
55 
1-36500 
0-59997 
2-64317 
1-99014 
15 
II. 
I. 
P15060 
0-50585 
2-22810 
1-67695 
16 
55 
55 
1-27475 
0-56049 
2-46936 
1-85794 
17 
55 
55 
2-54096 
1T1688 
4-92047 
3-70420 
