BAXTER. 



ATOMIC WEIGHT OF CHROMIUM. 



413 



tions in the weight of the tube were never much larger than the probable 

 error in weighing the tubes. 



As is to be expected, the water content gradually decreases with 

 increasing temperature of heating. The extreme variation with speci- 

 mens of silver chromate which have been heated at 225° amounts to 

 only five thousandths of a per cent. Evidently the percentage of re- 

 sidual water is as constant as can be reasonably expected, and the mean 

 can safely be assumed to represent with sufficient exactness the average 

 proportion of water in the salt. Hence from every apparent gram of 

 silver chromate 0.000144 gram is subtracted. 



Density of Silver Chromate. 



In order to correct the weight of silver chromate to a vacuum stand- 

 ard, a knowledge of its specific gravity is necessary. This has already 

 been determined by Playfairand Joule 29 and Schroeder, 30 who obtained 



The following vacuum corrections were applied 



29 Mem. Chem. Soc, 2, 401 (1845). 



30 Lieb. Ann., 173, 72 (1874). 



