f 



I 



I 



r, 



/. TV. Mallet on the Separation of Lithia and Magnesia. 137 

 acid.* The solution afforded the followiDg constituents in the 



ratios annexed : 



Alumina, 



Lime, 



Protoxjd of iron, 



Magnesia, 



13-00 



4-00 



1-80 



•50 



•which coupled with the concurring mineralogical and blowpipe 



evidence of the character of the leading constituent of the stone, 



I leave no doubt of its being true anorthite. The pyroxene, chlad- 



nite and olivine, afforded each, the usual blowpipe proofs of 

 their agreement with those species, respectively. 



The following may be taken as a tolerably close approxima- 

 tion to the mineral constitution of the Petersburg stone: — 



\ Anorthite, 



i Chladnite, - 



Olivine, 



Pvroxene, • 



82-0 p. c, 

 9 " 

 50 

 1-0 



u 



Nlckeliferous iron, - - - - - 2*5 



Chromite and pyrites, » • - • 0'5 



u 



{^ Charleston, S. C, March 21, 1867. 



100 



\ Art. XIL — On the Separation of Magnesia and LitMa; by 



J. W. Mallet^ Ph.D. 



[Concluded from vol. xxiii, p. 430.] 



It having been found that the two bases under consideration 

 could not be accurately separated by ignition as chlorids -^'ith 

 oxyds of mercury, anotner experiment was made with the same 

 reagent, carrying the heating no higher than lOO"" C. Precipita- 

 ted oxyd of mercury was employed instead of the finely pulver- 

 ized crystalline oxyd which had been used in the former experi- 



I ments. The magnesia alone was quantitatively determined. 



(1.) -3463 grm. of pure MgO was dissolved in muriatic acid^ 

 mixed with about '4000 grm, of LiCl in solution in water, and 

 the mixture gradually evaporated to dryness over a steam-bath 



) along with an excess of pure freshly precipitated oxyd of mer- 



cury. When the mass had become perfectly dry, it was again 

 moistened with water, again dried at 100°, once more moistened, 

 and a third time thoroughly dried. It was now treated with 

 boiling water, the fluid filtered, and the insoluble matter remain- 



• The silicic acid could not be separated from the undecomposed cUadnite, oli- 

 vine and pyroxene. 



SECOND SERIES, VOL, XIIV, NO. 70. — JULY, 1957^ 



18 



