76 ATOMIC WEIGHT DETERMINATIONS. 



bouate containing ammonia in excess. All weighings re- 

 duced to vacuum. {Stas, Untersuch. iiber Chem. Prop., 

 Leipzig, 1867.) 



MAGNESIUM. 



Kegnault and Kopp have each determined the specific 

 heat of this metal. It answers to an atomic weight of 

 about 24. {Gmelin-Kraut, L c.) 



J. J. Berzelius : ^6.3 (0 = 16) ; 158.139 (0 = 100). 



Determined by dissolving magnesium oxide in dilute sul- 

 phuric acid, evaporating and heating to incipient redness. 

 100 oxide were found = 293.985 sulphate. The sulphate 

 was perfectly soluble in water and had therefore lost none 

 of its acid. The oxide was purified by solution in an 

 aqueous solution of carbon di-oxide and reprecipitated by 

 boiling. S = 200.75. {Poggend. Ann., 8, 1826, 188; and 

 Lehrbuch, 3, 1227.) 



Marchand and Scheerer recalculated this analysis for S = 

 200 and reached the value 157.74. They assert that the 

 oxide may have contained alkalis and that the sulphuric 

 acid carries oft* magnesium sulphate in volatilizing. [Erd- 

 mann' s Journ. filr Prak. Chem., 50, 1850, 392.) 



W. Henry : F. H. Wollaston : 23.36 (0 = 16); 146 

 (O = 100). 



Henry found that magnesium sulphate contained 33 per 

 cent, magnesium oxide. If S = 200 the value follows. 

 [Phil Trans., 104, 1814, 21.) 



— LoNGcnAMP : 15.35 (0 = 16). 



In two experiments, Longchamp found that five parts of 

 crystallized magnesium sulphate are equivalent to 4.91 

 barium sulphate. [If Ba = 137.08 ; S = 32, the number 

 follows.] Longchamp found 53 per cent, water which is 

 much too high. According to Marchand and Scheerer, the 

 data for the anhydrous salt give Mg = 97.37, for S = 200 ; 

 Ba = 856.8, [or 15.74.] [Annal de Chirn. et de Phys., 12, 

 1819, 265.) 



L. J. Gay-Lussac : 23.62 (O = 16). 



16.205 grammes crystallized sulphate were found equal 

 to 15.345 barium sulphate, and 19.395 magnesium sulphate 



