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wails 
and the formation of Gypsum and Magnesian Rocks. 375 
ate. A pose and nearly white fragment gave to hydrochloric 
acid, carbonate of magnesia 83:35, carbonate of iron 9-02, and 
left insoluble 8-03=100-40 ;. while another specimen from the 
same mass contained, carbonate of magnesia 33-00, carbonate of 
iron 19°35, alumina 0:50, insoluble 45°90=98:70. In both cases 
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vesce with cold hydrochloric acid, which however readily dis- 
Solves them with the aid of heat. The decomposition i 
i surfaces 
contained carbonate of iron renders their weat: 
fy Me. W. P. Blake, who also found a bed of nearly pure white 
t carbonate of magnesia am 
that region, I may see cmalll the existence of beds of magne- 
site among argillites in Styria, and also in the ancient crystalline 
gneiss of Modum in Norway, where a crystalline magnesite is 
the gangue of crystals of serpentine and ilmenite—(Am. Jour, 
of Science, (2), v, 389.) 
