STRONTIUM. 113 



The antecedent values are 



O = 15.879, .0003 c= 11.920, .0004 



Ag = 107.108, .0031 S =31.828, -0015 



Hence the subjoined values for the atomic weight of calcium : 



From (i) .......................... Ca = 39.757, dz .0048 



From (2) ... ...................... " = 39.925, .0203 



From (3) ................. ........ " == 39-706, .0204 



From (4) ......................... " = 39.868, HE .0503 



Mean Ca = 39.764, .0045 



If = 16, Ca = 40.067. 



STRONTIUM. 



The ratios which fix the atomic weight of strontium resemble in gen- 

 eral terms those relating to barium, only they are fewer in number and 

 represent a smaller amount of work. The early experiments of Stro- 

 meyer,* who measured the volume of CO 2 evolved from a known weight 

 of strontium carbonate, are hardly available for the present discussion. 

 So also we may exclude the determination by Salvetat,f who neglected 

 to publish sufficient details. 



Taking the ratio between strontium chloride and silver first in order, 

 we have series of figures by Pelouze and by Dumas. Pelouze J employed 

 the volumetric method to be described under barium, and in two ex- 

 periments obtained the subjoined results. In another column I append 

 the ratio between SrCl 2 and 100 parts of silver : 



1.480 grm. SrCl 2 = 2.014 grm. Ag. 73-486 



2.210 " 3.008 " 73-47 1 



Mean, 73.4781, db .0050 



Dumas, by the same general method, made sets of experiments with 

 three samples of chloride which had previously been fused in a current 

 of dry hydrochloric acid. His results, expressed in the usual way, are 

 as follows : 



* Schweigg. Journ., 19, 228. 1816. 



f Compt. Rend., 17, 318 1843. 



I Compt. Rend., 20, 1047. 1845. 



I Ann. Chim. Phys. (3), 55, 29. 1859. Ann Cheat. Pharm., 113, 34. 



