MAGNESIUM. SCHEERER. ICM) 



This value must be considered as the most reliable 

 determination. The range of the four determinations of 

 this third series was 50. 



Now this mean value of the analytical ratio is exactly n 

 low of the atomic ratio, which is 



Mg O : Mg Oa C == 40 : 84 = 0.47 619. Change 62 high. 



The analytical excess being n low, corresponds therefore 

 to the atomic weight 0.018 low, or say Mg = 23.982 or better 



23-98. 



But to state this as the true value would imply the disre- 

 gard of actual errors of the chemical work. 



The range of 50 represents an uncertainty of 0.08 in total 

 range, or perhaps more fairly of 0.04 on the mean. 



In the summary of Clarke (p. 140) all three series made 

 with Frankenstein magnesite are, of course, combined, 

 giving 0.47 628 as final mean, which is 9 high. 



The Snarum magnesite gives him 0.47 624, which is 5 

 high. 



His final mean is 0.47 627, which is 8 high. 



Restricting ourselves, on principle, to the purest material 

 used, makes our analytical ratio 0.47 608, which is n low. 



The three series made with Frankenstein magnesite 

 would have given 9 high, the Snarum magnesite 5 high and 

 the mean of all 8 high. 



These analytical excesses correspond respectively to a 

 rise of 0.014, 0.008 and 0.013 on the atomic weight of 24. 



The third series alone, made upon the purest material, 

 gave us the analytical excess of n low, which would 

 correspond to a lowering of the true atomic weight o.oiS 

 below the standard 24. 



We can therefore truly say that, taking the series we 

 deem the most conclusive, or taking all or indeed any one, 

 the difference between the true and standard atomic weight 

 cannot reach 0.02 either way. 



Accordingly, the dry way work on magnesite, instituted 

 by Marchand and finished by Scheerer fully half a century 

 ago, establishes, as a fact, by experimental work of highest 

 order, that the true atomic weight of magnesium is not 



