214 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



Per cent. SO,. Ratio, MgSO^.BaSOt. 

 66.G7 194.177 



6G.73 194.351 



66.G4 194.089 



66.65 194.118 



66.69 194.239 



In another experiment 60.05 grains MgS04 gave 116.65 grains BaSO^, 

 a ratio of 100 : 194.254. Including this with the preceding figures, they 

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

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



MgSO^iBaSO,: : 100: 194.003, ± .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. 



From Macdonnell's data the atomic weight of magnesium ranges be- 

 tween 24.00 and 24.43. 



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

 verted 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 grm. MgO gave 5.0157 grm. MgSO^. 296.122 



2.0459 " 6.0648 " 296.437 



1.0784 " 3.1925 " 296.040 



Mean, 296.200, ± .0815 



Hence Mg = 24.812. 



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

 Svanberg and ISTordenfeldt'' 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 was as follows: 



7.2634 grm. oxalate gave 1.9872 grm. oxide. 27.359 per cent. 



6.3795 " 1.7464 " 27.875 



6.3653 " 1.7418 " 27.364 



6.2216 " 1.7027 " 27.368 



Mean, 27.3665, ± .0023 



Hence Mg= 24.706. 



^ Journ. prakt. Chem., 56, 310. 1852. 

 ='Journ. prakt. Chem., 45, 473. 1848. 



