MAGNESIUM. 145 



With the aid of these intermediate values, four estimates of the atomic 

 weight of magnesium are available, as folloAvs : 



From molecular weight of MgSO^. . . . Mg = 24,099, ±: .0136 



From molecular weight of MgO " = 24.095, ± .0014 



From molecular weight of MgClj " = 24.194, =t .0099 



From ratio (6) " ^24. 103, ± .0020 



General mean Mg = 24. 100, ± .001 1 



If = 16, this becomes Mg = 24.283. 



On purely chemical grounds the third of the foregoing values, that 

 derived from magnesium chloride, seems to be the best. I should un- 

 hesitatingly adopt it, rejecting the others, were it not for the fact that it 

 rests upon one compound of magnesium alone, and therefore is not ab- 

 solutely conclusive. It agrees admirably, however, with the sulphate 

 determinations of Marignac, and it is highly probable that it may be 

 fully confirmed later by evidence from other sources. 



Marignac's data, taken alone, give Mg = 24.197. The fourth series of 

 Richards and Parker, by itself, gives INIg = 24.180. The approximate 

 mean of these, 24.19, may be preferred by many chemists to the general 

 mean derived from all the observations. 



10 



