870 PROCEEDINGS OP THE AMERICAN ACADEMY. 



1843, Salvetat * determined by loss of weight the carbon dioxide in 

 strontic carbonate, and concluded that the metal must be 88.0, — a 

 result which scarcely improved the situation. 



Subsequently, in 1845, Pelouze f found the amount of silver neces- 

 sary to precipitate a weighed amount of ignited strontic chloride ; his 

 results give the value Sr = 87.70. Thirteen years later Marignac X 

 repeated these experiments, determining also the amount of crystal 

 water in crystallized strontic chloride, as well as the amount of stron- 

 tic sulphate obtainable from the salt. Thus he found that 15.000 

 grams of crystallized strontic chloride yielded 8.9164 § grams of the 

 anhydrous salt and 10.3282 grams of strontic sulphate ; moreover, 

 15.000 grams of hydrated strontic chloride required 12.1515 grams of 

 silver for precipitation. Another similar series of experiments upon 

 the water of crystallization made its amount appear three milligrams 

 more than before. These data give basis for a number of possible 

 values for the atomic weight of strontium, ranmns: from 87.17 to 

 87.55, the individual figures being tabulated below. 



In 1859 Dumas || published another determination of the ratio of 

 strontic chloride to silver, the salt having been fused in a stream of 

 hydrochloric acid. Altogether, 27.3435 grams of strontic chloride 

 required in his hands 37.252 grams of silver, the individual values 

 for strontium varying fi'om 87.3 to 87.8. Since this time the sub- 

 ject has remained untouched. 



Below is tabulated a list of the various determinations, grouped 

 according to the ratios determined. 



The Atomic Weight of Strontium. 



Oxygen = 16.000. 



From the carbonate : 



Stromeyer, 1816 87.30 



Salvetat. 1843 88.00 



Ratio of strontic and argentic chlorides : 



Rose, 1816? 87.31 



* Comptcs Eendus, XVII. 318. 



t Ibid., XX. 1047. 



X Liebig's Annalcn, CVI. 168. 



§ Corrected V)y L. Meyer u. K. Seubert, Atomgewichte, pp. 78, 79. 



II Liebig's Annalen, CXIII. 34. 



