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. CO 2 = 8.2245 grm. MgO. 47.760 per cent. MgO. 



7-960 " 7.2775 " 47.76i 



9-3 2 65 8.529 47.767 



7-553 " 6.9095 " 47-775 



Mean, 47.766, .0022 



This mean, corrected for loss of C0 2 in drying, becomes 47.681. I give 

 series second with corrections applied : 



6.8195 S rm - MgCO 3 gave 3.2500 grm. MgO. 47.658 per cent. 



11.3061 " - 5-3849 " 47.628 " 



9-7375 " 4-635 (( 47-599 " 



12.3887 5.9033 47.650 



32.4148 15.453 47-674 " 



38.8912 18.5366 " 47.663 " 



26.5223 12.6445 " 47.675 " 



Mean, 47.650, d= .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. MgCO 3 gave 2.0436 grm. MgO. 47.622 per cent. 



27.8286 " 13-2539 " 47.627 " 



14.6192 " 6.9692 " 47.672 " 



18.3085 '< 8.7237 " 47-648 " 



Mean, 47.642, =fc .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 escaped notice in the original analyses. With this correction 

 the two magnesites in question exhibit the following mean composition : 



Snarum. Frankenstein. 



C0 2 52.131 52.338 



MgO 46.663 47-437 



CaO 430 . 225 



FeO. 776 



100.000 100.000 



Correcting for lime and iron, by assigning each its share of C0 2 , the 

 Snarum magnesite gives as the true percentage of magnesia in pure 



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



