Seyherfs Analysis of the Maclureite. 343 



E. The magnesia was precipitated from the liquor (D), 

 with an excess of caustic potash, after a strong calcina- 

 tion it weighed 1.62 grammes on 3 grammes, or 54.00 

 per 100. 



The constituents of this mineral are therefore. 



Per 100 Parts. 



A. Water 01.000 Containing Oxygen. 



B. Fluoric Acid 04.086 02.971 

 G. Silica 32.666 16.430 



D. Per Oxide of iron 02.333 00.715 



E. Magnesia 54.000 20.90i 

 Analysis(No.2)F.Potash 02.108 00.357 



96.193 

 100.000 



003.807 Loss. 



In regarding this analysis according to the theory of 

 chemical proportions, this mineral evidently consists of an 

 atom of sub-fluate of Magnesia, combined with three atoms 

 of silicate of Magnesia, the fluate of Potash and silicate of 

 Iron being unessential ingredients, therefore its mineralo- 

 gical formula will be M" ~Z + 3MS. 



The subject of the preceding examination, I have been 

 told, was discovered several years ago, by the late Dr. 

 Bruce, near Sparta, in Sussex Co. New-Jersey. When 

 our mineralogists became first acquainted with thissubstance, 

 it was supposed to be Sphene : subsequent investigations led 

 to its being ranked with the Condrodite, a mineral discov- 

 ered in Sweden, and analysed by M. d'Ohsson. The ex- 

 periments of this gentleman were repeated and verified by 

 Professor Berzeluis the results were as follows : viz. — per 

 100, Silica 38. Magnesia 54, Oxide of Iron 5.1, Alumi- 

 na 1.5, Potash 0.86, Manganese a trace, loss 0.54.* From 

 the preceding summary, it is evident that the two substances 

 are essentially different in their chemical composition, though 

 they much resemble each other in their physical characters. 

 Magnesia not having heretofore been found combined with 



* Journal of the Royal Institution of G. B. 1852, No. 24. 



