MAGNESIUM. 137 



Secondly, anhydrous magnesium sulphate was precipitated with ba- 

 rium chloride. From the weioht of the barium suljjhate, with SO3 = 

 80 and Ba = 137, Macdonnell computes the percentaa;es of SO, given 

 below. I calculate them back to the observed ratio in uniformity with 

 Scheerer's work : 



Per cent. SO-,. Ratio, MgSO^ : BaSO,. 

 66.67 194-177 



66.73 194.35' 



66.64 194.089 



66.65 194. 118 

 66.69 194.239 



In another experiment 60.05 grains MgSO^ gave 116.65 grains BaSO^, 

 a ratio of 100 : 194.254. Including this with the preceding tigures, the}^ 

 give a mean of 194.205, dr .027. This, combined with the work of 

 Scheerer and Jacquelain, 193.700, rh .033, gives a general mean of — 



MgSO^ : BaSO^ : : loo : 194.003, zb .021. 



In one final experiment Macdonnell found that 41.44 grains of pure 

 magnesia gave 124.40 grains of MgSO^, or 300.193 per cent. 



Bahr's * work resembles in part that of Jacquelain. This chemist 

 converted pure magnesium oxide into sulphate, and from the increase 

 in weight determined the composition of the latter salt. From his weigh- 

 ings 100 parts of MgO equal the amounts of MgSO^ given in the third 

 column : 



1.6938 gim. MgO gave 5.0157 grm. MgSO^. 296.122 



2.0459 " 6.0648 " 296.437 



1.0784 " 3-19-5 " 296.040 



Mean, 296.200, =b .0S15 



About four years previous to the investigations of Bahr the paper of 

 Svanberg and Nordenfeldt f appeared. These chemists started with the 

 oxalate of magnesium, which was dried at a temperature of from 100° 

 to 105° until it no longer lost weight. The salt then contained two 

 molecules of water, and upon strong ignition it left a residue of MgO. 

 The percentage of MgO in the oxalate comes out as follows : 



7.2634 grm. oxalate gave 1.9S72 grm. oxide. 27.359 per cent. 



6-3795 " 1-7464 " 27.375 " 



6.3653 " I-741S " 27.364 " 



6.2216 " I-7027 " 27.368 " 



Mean, 27.3665, ± .0023 



* Journ. fur Prakt. Chem., 56, 310. 1852. 

 t Journ. fur Prakt. Chetn., 45, 473. 1S4S. 



