342 Extract from the third Volume of 



Carbonate of lime _ _ _ _ 53-00 



Carbonate of magnesia _ _ _ 42"30 



Carbonate of iron mixed with a little magnesia 3-00 



98-30 



The proportion of the principles of miemitCj which ap- 

 proaches very near to that of the magnesian spar of the 

 Tyrol, ought to make them be considered as two species 

 of the same kind. 



Analysis of prismatic Magnesian Spar. 



This spar, discovered at Gluuk Bronn, in the country of 

 Gotha, in veins of cobalt, is very rare : its crystals are tetra- 

 edral, almost rectangular, of an asparagus green colour, 

 darker in several varieties than that of the chrvso-bcryl, and 

 rarely so clear as that of the apatite of Cape Gates. They 

 exhibit a vitreous splendour in their fracture ; they break in 

 irregular angular fragments ; thcv are very pellucid, and of 

 a mean hardness ; they leave a snow-white trace ; their spe- 

 cific gravity is 2-8S5. 



Some crvstals of i.iagnesian spar, calcined in a platina 

 crucible for half an hour, came from it entire; but exceed- 

 higly friable, and altogether opake. Zones of different co- 

 lours, the interior of u'hich was Isabella yellow, were ob- 

 served in them ; the second was reddish white, and the 

 nucleus pink brown : they retained also some t;plcndour, 

 and had lost 43 per cent, of carbonic acid, though the whole 

 acid was not then entirely volatilized. A hundred parts of 

 magnesian spar contain 



Lime _ _ _ 



Magnesia 



Oxide of iron 



Carbonic acid 



Water and loss 



Analysis of Egyptian ]\aty?/.m. 

 We arc indebted to M. Berthollct for the most correct 

 description of the lakes of natrum, and of the deserts of 

 Makaria in Lower Egypt. The natrum ibund there is not 

 all of equal purity : from time innnemorial it has been an 

 important article of commerce. 



The 



