MAGNESIUM. 



139 



Of the white magnesite from Snarum but a single analysis was made, 

 which for present purposes may be ignored. Concerning the Franken- 

 stein mineral three series of analyses were executed. In the first series 

 the following results were obtained : 



8.996 grm. COj^ 8.2245 grm. MgO. 47.760 per cent. MgO. 



7.960 " 7-2775 " 47-761 



9.3265 " 8.529 " 47-767 



7-553 " 6.9095 " 47.775 



Mean, 47.766, ± .0022 



This mean, corrected for loss of CO.^ in drying, becomes 47.681. I give 

 series second with corrections applied : 



Mean, 47.650, it .0069 



The third series was made upon very pure material, so that the cor- 

 rections, although applied, were less influential. The results were as 

 follows : 



4.2913 grm. MgCOj gave 2.0436 grm. MgO. 47.622 per cent. 



27.82S6 " 13-2539 " 47-627 



14.6192 " 6.9692 " 47-672 " 



18.3085 " 8.7237 " 47-648 " 



Mean, 47.642, ± .0077 



In a supplementary paper* by Scheerer, it was shown that an impor- 

 tant correction to the foregoing data had been overlooked. Scheerer, re- 

 examining the magnesites in question, discovered in them traces of lime, 

 which had esc"aped notice in the original analyses. With this correction 

 the two magnesites in question exhibit the following mean composition : 



Snarum. Frankenstein. 



CO2 52.131 52-338 



MgO 46-663 47-437 



CaO 430 .225 



FeO 776 



100.000 



Correcting for lime and iron, b}'' assigning each its share of COj, the 

 Snarum magnesite gives as the true percentage of magnesia in pure 



* Ann. d. Chem. und Pharm., no, 240. 



