CHROMIUM. 119 



periment the anhj'drochromate Ag-jCrjOT was used. These 

 salts, which are easily obtained in a perfectly pure condition, 

 were reduced in a large flask by means of hydrochloric acid 

 and alcohol. The chloride of silver thus formed was washed 

 by decantation, dried, fused, and weighed without transfer. 

 The united washings were supersaturated with ammonia, 

 evaporated to dryness, and the residue treated with hot 

 water. The resulting chromic oxide was then collected 

 upon a filter, dried, ignited, and weighed. The results were 

 as follows : 



4.66S0 grm. Ag.jCr04 gave 4.027 grm. AgCl and 1.0754 gnu. Cr^Oj. 



3.4568 " 2.983 " .7960 



2.5060 " 2.1605 " -5770 " 



2.1530 " 1.8555 " -4945 



4-3335 grm- AgjCi-p, gave 2.8692 " 1.5300 



From these weighings three values are calculable for the 

 atomic weight of chromium. The three ratios upon which 

 these values depend we will consider separately ; taking first 

 that between the chromic oxide and the original silver salt. 

 In the four analyses of the normal chromate the percentages 

 of CrgOs deducible from Berlin's weighings are as follows : 



And from the single experiment with Ag^Cr^.O, the per- 

 centage of Cr^Oj was 35.oOG. 



For the ratio between AgjCrO^ and AgCl, putting the 

 latter at 100, we have for the former : 



"5-917 

 115-883 

 115.992 

 116.033 



Mean, 115.956, ±.023 



