BAXTER AND JESSE. 



ATOMIC WEIGHT OF CHROMIUM. 



429 



The negative corrections as found above are applied to all the final 

 weights of silver dichromate given in the table of analyses. 



The Specific Gravity of Silver Dichromate. 



The specific gravity of silver dichromate has been found by Schroder 7 

 to be 4.669, but on account of the uncertainty of most of the older spe- 

 cific gravity determinations this constant was very kindly redetermined 

 for us by Mr. Victor Cobb. The silver dichromate was precipitated 

 from dilute nitric acid solution and once recrystallized from normal 

 nitric acid. Then it was dried at 200° for many hours. The determi- 

 nation was effected by displacement of toluol of specific gravity 0.86218. 

 Care was taken to extract entangled air from the crystals by exhausting 

 the air from the pycnometer in a vacuum desiccator. 



The following corrections were applied 



A No. 10 Troemner balance easily sensitive to one fiftieth of a milli- 

 gram was used in all the weighings. The gold-plated weights were 

 carefully standardized to hundredths of a milligram by the method 

 described by Richards. 8 



Weighing was always carried out by substitution, with the use of a 



7 Liebig's Jahresb., 1879, 31, 



• Jour. Amer. Chem. Soc, 22, 144 (1900). 



