ATOMIC AYEIGHTS 181 



calcium chloride was first ignited in a stream of dry hydrochloric acid, 

 and the solution of this salt was afterwards titrated with a silver solution 

 in the usual way. The CaCl, proportional to 100 parts of Ag is given 

 in a third column : 



Mean, 51.4554, ±: .0230 



Hence Ca = 40.103. 



Better results were obtained by Richards.' Calcium chloride, purified 

 by repeated crystallizations, and fused in a stream of nitrogen, was 

 precipitated by a solution of silver, and the silver chloride so produced 

 was weighed. The data, with vacuum weights, are subjoined : 



1.56454 grm. CaCl, gave 4.0409 AgCl. Ratio, 38.7177 



3.57630 " 9.2361 " " 38.7209 



3.59281 " 9.2788 " " 38.7206 



5.00880 " 12.9364 " " 38.7187 



9.00246 " 23.2506 " " 38.7197 



Mean, 38.7195, ± .0004 



Hence Ca = 40.083. 



There are now five independent ratios for calcium, as follows : 



(1). CaCOsiCaO: :100:56.0603, ± .0003 

 (2). CaOiSOs: : 100: 142.3998, ± .0518 

 (3). CaCOsiCaSO,: : 100: 136.0525, ± .0071 

 (4). 2Ag:CaCL::100:51.4554, ± .0230 

 (5). 2AgCl:CaCL: : 100: 38.7195, ± .0004 



Journ. Amer. Chem. Soc, 24, 374. 1902. 



