572 PROFESSOR DITTMAR AND MR JOHN M'ARTHUR ON 



"Miso" for the same, dried in addition for 23 hours at 150° C. 



The number for the loose chlorine suggests the presence of 000504 x (0 = 16 

 parts of oxygen) in the PtX 4 part of the salt. Admitting this, we have, if 

 Pt = 196-58, for the composition of M parts of this kind of chloroplatinate— 



Platinum, 196-58 



2KC1, 149-18 



1-99496 xCl 2 , 141-46 



0-00504x0, . . . . . • 008 



487-30 

 Hence water, &c. in. 



M no . and M 150 . 



Per M parts, . . . 3-79 1-87 



Percent., .... 0-771 0-381 



TJie oxychloride oxygen amounts to very little, supposing it to be present 

 at all. Taking the two determinations of the total chlorine as so many 

 determinations of three times the fixed chlorine, and combining them with 

 the direct determination of the latter, we had : — 



Mean value of fixed chlorine = 042401 ; and for 2KC1 parts 



Platinum, 196-80 



2KC1, 149-18 



4C1, 14182 



PtCl 6 K 2 , 48780 



and for the values M, 



M 110 = 491-64; M 150 = 489-72. 

 and for water, etc., in these, 



Per M parts, .... 3-84 1-92 



The results remain substantially the same. 



Experiment VI. (Matthey's Metal). 



At the time when this experiment was planned, we had arrived at the 

 conviction that the atomic weight of platinum is very nearly, if not exactly, 

 equal to 196, and the object of the experiment was to test this number in the 

 most direct manner possible, namely, as follows : — 



0-7548 grm. of chloride of potassium was dissolved in 20 c.c. of water, and 

 the solution transferred to a tared glass-stoppered bottle of about 120 c.c. 

 capacity. 20-5 c.c. of standard platinum solution were then measured out, 

 weighed exactly, and added to the chloride of potassium. From the weight 

 and the known titre of the solution, it followed that the weight of 

 platinum added amounted to 0-99086 grm. or to 1959 per 2KC1. The idea 

 was to let the chloroplatinate separate out as far as possible, to draw off some 



