CALCIUM. 107 



Erdmann and Marchand, 1844. Iceland Spar. 



;,* , 4.2134 2.3594 0.55 997 3 low. 



2 I5'I385 8.4810 0.56 022 22 high. 



3 23.5503 13.19$$ 0-56 031 31 high. 



4 23.6390 13-2456 -56 <>3 2 32 high. 



5 42-0295 23.5533 0.56 044 44 high. 



6 49.7007 27.8536 0.56 042 42 high. 



Mean 0,56 028 28 high. 



1850, i Det., Artif. Carb., 0.55 998 2 low. 



This last case made with utmost care. Combined with 

 the mean of the four determinations on artificial carbonate, 

 the general mean would be i high, i corresponding to 40.01. 

 Ca O4 S : Ca Os C = 136 : 100 = 1.36 ooo. Change 36 low. 

 Erdmann and Marchand^ 1842. (Annales T. 8, p. 216): 



This mean would correspond to 39.85. 



For Ca = 40, change to S = 32.1 would give ico high. 



Hence, 55 high would correspond to S = 32.055. 



Ca Ch : Ag2 = in : 216 = 0.51 389. 

 Dumas, 1859. Volumetric. 



2 3 gr. Det. 5, Extr. 573 394; 179. Mean 66 high. 



Since for 40.1 the ratio would be 46 high, this mean 

 would correspond to Ca = 4o.i4, while the range 179 corres- 

 pond to a range of 0.4 or one per cent of the total atomic 

 weight. 



I understand that T. W. Richards has also made deter- 

 minations, probably on the bromide, as he is wont to do; 

 compare his work for Mg, Sr, Ba, Zn. It is all of the same 

 general character. 



The results obtained by the dry and the wet way differ in 

 accuracy as was stated in an earlier section, pp. 46-55. 



