43 



TRANSLATIONS AND NOTICES 



OF 



GEOLOGICAL MEMOIRS. 



On Magnesite, and the Economic production of Sulphate of 

 Magnesia. Bv M. Foetterle. 



[Proceedings of the Imp. Geol. Instit. Vienna, Jan. 9, 1855.] 



M. Foetterle notices a new locality of Magnesite, discovered 

 by him during his geological survey, in the environs of Bruck in 

 Styria. Considerable masses of this mineral occur north of Bruck 

 in a limestone imbedded in crystalline slates. It closely resembles 

 crystalline limestone both in its structure and its white colour. 



The angle of the rhombohedron obtained by cleavage is 107° 16' ; 

 specific gravity, 3 '033 ; hardness, 4*5, according to Mohs' scale. 

 M. C. V. Hauer found it to contain 99*2 per cent, of carbonate of 

 magnesia, and a very slight quantity of carbonate of iron. When 

 interspersed with minute particles of iron pyrites, it gives 94*7 per 

 cent, of carbonate of magnesia. 



Besides the locality just mentioned, three other localities in the 

 Alpine grauwacke, viz. Gloggnitz, Neuberg, and Trieben, aiford still 

 larger quantities of Magnesite. 



M. Foetterle dwells on the commercial importance of this mineral, 

 as a material for the profitable production of bitter-salt (sulphate of 

 magnesia), in the same manner as, according to M. Delesse, the 

 manufacture of* this salt from serpentine has become an extensive 

 branch of industry in France. The serpentine, after having been sub- 

 mitted to calcination for forty-eight hours, is reduced to fine powder, 

 and then treated with dilute sulphuric acid. A somewhat less quantity 

 of the acid is used than would be required to saturate the whole 

 amount of the magnesia in the serpentine. The solution, freed from 

 all heterogeneous substances, is left to crystallize in wooden tubs ; 

 and pure sulphate of magnesia is obtained by the second cry- 

 stallization. 



M. Malapert, at Chatre, and MM. Mallet and Lapellier, at Caen, 

 have used with success the method employed in England to obtain 

 this salt from dolomite. The dolomite is treated with 94 per cent, 

 of its weight of sulphuric acid ; the filtered solution is freed from 

 the sulphate of lime, filtered again, concentrated, and finally left to 

 crystallize in stone reservoirs. This new branch of industry has 

 enabled France to dispense with the importation of foreign sulphate 

 of magnesia. 



[Count M.] 



vol. xi. part ii. f 



