PLATINUM. 329 



If these series are treated as independent and combined, giving each 

 a weight as indicated by its probable error, and regarding tlie single ex- 

 periment with preparation II as equal to one in the first series, we get 

 a mean percentage of 43.907, ± .0009. On the other hand, if w^e regard 

 the twenty-two experiments as all of equal weight in one series, the mean 

 percentage of platinum becomes 43.953, ± .0078. Upon comparing the 

 work with that done later by Halberstadt, the latter mean seems the fairer 

 one to ado])t. 



For the chlorine estimations in the ammonium salt, Seubert gives the 

 subjoined data. I add in the last column the weight of salt proportional 

 to 100 parts of silver chloride. 



Mean, 51.864, =b .041 



The potassium salt, K^PtClg, was also analyzed by ignition in hydro- 

 gen, treatment with water, and weighing both the platinum and the 

 potassium chloride. The weights given are as follows : 



K.,PICI^. Pt. 2KCI. 



5.0283 2.0173 1.5440 



7.0922 2.8454 2.1793 



3-5475 1-4217 1.0890 



3.2296 I. 2941 .9904 



35834 1.4372 i.iooi 



4-4232 1.7746 1.3547 



4.0993 1.6444 1.2589 



4.4139 1. 7713 1. 3516 



Hence we have these percentages, reckoned on the original salt : 



Pt. KCl. 



40.119 30.706 



40.120 30.728 

 40.076 30.698 

 40.070 ' 30.666 

 40.107 30.700 

 40.120 30.627 

 40.114 30.710 

 40.130 30.621 



Mean, 40.107, ± .005 Mean, 30.682, ± .009 



As with the ammonium salt, three experiments were made upon the 

 potassium compound to determine the amount of chlorine (four atoms 

 in this case) lost U))on ignition in hydrogen. In the fourth column I 

 add the amount of K.^PtClg corresj^onding to 100 parts of AgCl : 



