CHROMIUM. 241 



1.2615 g rm - BaCrO 4 gave 1.1555 g rm - BaSO 4 . 109.174 



1.5895 " L458o " 109.019 



2.3255 " 2.1340 108.974 



3.0390 2.7855 " 109.101 



2.3480 2.1590 " 108.754 



1.4230 1.3060 u 108.708 



I.I975 1.1005 108.814 



3.4580 " 3-1690 " 109.119 



2.0130 1.8430 " 109.224 



3.5570 " 3-2710 " 108.744 



1.6470 " 1.5060 " 109.363 



1.8240 1-6725 " 109.058 



1.6950 " 1.5560 " 108.933 



2.5960 " 2.3870 " 108.756 



Mean, 108.9815, .0369 



Wildenstein,* in 1853, also made barium chromate the basis of his 

 researches. A known weight of pure barium chloride was precipitated 

 by a neutral alkaline chromate, and the precipitate allowed to settle until 

 the supernatant liquid was perfectly clear. The barium chromate was 

 then collected on a filter, washed with hot water, dried, gently ignited, 

 and weighed. Here again arises the objection that the precipitate may 

 have retained traces of alkaline salts, and again we find deduced an 

 atomic weight which is too high. One hundred parts BaCr0 4 correspond 



to BaCl 2 as follows : 



81.87 81.57 



81.80 81.75 

 81.61 81.66 

 81.78 81.83 

 81.52 81.66 



81.84 81.80 



81.85 81.66 

 81.70 81.85 

 81.68 81.57 



81.54 81.83 

 81.66 81.71 



81.55 81.63 



81.81 81.56 



81.86 81.58 

 81.54 81.67 

 81.68 81 84 



Mean, 81.702, .014 



Next in order we have to consider two papers by Kessler, who em- 

 ployed a peculiar volumetric method entirely his own. In brief, he com- 

 pared the oxidizing power of potassium dichromate with that of the 

 chlorate, and from his observations deduced the ratio between the mo- 

 lecular weights of the two salts. 



t Journ. fiir Prakt. Chem., 59, 27. 



16 



