78 ATOMIC WEIGHT DETERMINATIONS. 



caustic magnesia formed. The carbonate was dried at 

 300°, and the carbon di-oxide, which passes off above 230°, 

 was caught by caustic baryta solution and determined. The 

 traces of carbon di-oxide not expelled by a yellow heat 

 were set free by solution in chlorhydric acid and also de- 

 termined as barium carbonate. The silicic acid, etc., were 

 also determined. The mean in air is 150.34 ; in vacuo as 

 above. Extreme difference, 0.57. C = 75. Eleven other 

 experiments were made with comparatively impure material 

 and less precaution, tending to confirm the above. (M'd- 

 mann's Journ. fiir Prak. Cliem.,60, 1850, 409.) 



T. ScHEERER : 24 (0 = 16) ; 150 (0 = 100). 



By separating the neutral sulphates of magnesium and 

 calcium by means of alcohol, Scheerer found that the mag- 

 nesites used by Marchand and himself contained from one- 

 fourth to one-half per cent, calcium oxide. This correction 

 would make their determination almost exactly 250 or 24. 

 {Liebifs Ann., 110, 1858, 236.) 



V. A. Jacquelin: 34,408 (O = 16); 152.55 (O = 

 100). 



Anhydrous, neutral magnesium sulphate, obtained by 

 solution of the oxide in sulphuric acid and heating to red- 

 ness, gave 33 56 per cent, pure oxide. The method adopted 

 is not described. This oxide by treatment with sulphuric 

 acid gave the original amount of sulphate. If S = 200, 

 the number follows. {Annal. de Chim. et de Phys., (3,) 32, 

 1851, 195.) 



A. Macdonnell : 23.9 (0 =16). 



Determined from analyses of anhydrous and of crystal- 

 tized magnesium sulphate. (Brit. Assoc. Pep., 1852, part 

 2, 36 ; and Kopp's Jahresbericht, 6, 364.) 



J. F. Bahr: ^^.77 (0 = 16) ; 154.842 (O = 100). 



A known weight of purified magnesium oxide was dis- 

 solved in sulphuric acid, evaporated and heated to redness 

 till the weight was constant. The number is the mean of 

 three experiments; extreme difference, 0.515. The oxide 

 was obtained from meteoric olivin. After removal of the 

 heavy metals, the solution was evaporated to dryness with 

 soda, washed and heated to redness. The oxide so obtained 

 was dissolved in acetic acid, oxalic acid was added, the 



