BARIUM. 123 



Turner * found that 100 parts of chloride ignited with sulphuric acid 

 gave 112.19 parts of sulphate. By the common method of precipitation 

 and nitration a lower figure was obtained, because of the slight solubility 

 of the sulphate. This point bears directly upon many other atomic 

 weight determinations. 



Berzelius,f treating barium chloride with sulphuric acid, obtained 

 the following results in BaS0 4 for 100 parts of BaCl 2 : 



112.17 

 112.18 



Mean, 112.175 



Struve, I in two experiments, found : 



112.0912 

 112.0964 



Mean, 1 12.0938 



Marignac's three results are as follows : 



8.520 grm. BaCI 2 gave 9.543 BaSO 4 . Ratio, 112.007 



8.519 9.544 " " 112.032 



8.520 " 9-542 " " ui-995 



Mean, 112.011, .0071 



Richards, in his work on this ratio, regards the results as of slight 

 value, because of the occlusion of the chloride by the sulphate. This 

 source of error he was never able to avoid entirely. Another error in 

 the opposite direction is found in the retention of sulphuric acid b} r the 

 precipitated sulphate. Eight experiments were made in two series, one 

 set by adding sulphuric acid to a strong solution of barium chloride in a 

 platinum crucible, the other by precipitation in the usual way. Rich- 

 ards gives in his published paper only the end results and the mean of 

 his determinations ; the details cited below I owe to his personal kind- 

 ness. The weights are reduced to vacuum standards : 



Bad.,. BaSO* Ratio. 



1.78934 2.0056 112.086 



2.07670 2.3274 112.072 



1.58311 i.774i 112.064 



3.27563 3- 6 7i2 112.076 



3.02489 3-393 112.080 



3.87091 4.3385 112.080 



(3.02489 3-9726 112.076 



nd - (3,87091 3.4880 112.085 



Mean, 112.077, .0017 



* Phil. Trans., 1829, 291. 



t Poggend. Annalen, 8, 177. 



1 Ann. Cheni. Pharm., 80, 204. 1851. 



g Journ. fi'ir Prakt. Chem., 74, 212. 1858. 



First. 



