228 M. Rose on those Minerals which possess [March, 



sparks with the steel, but with difficulty. It is in a high degree 

 translucent at the edges. Occurs in calcareous spar. It was 

 analysed by M. Rose, and the results obtained were: 



Silica. 54-86 containing oxygen 27*59 



Lime 23-57 6-62 



Magnesia 16-49 6-38 



Protoxide of iron 4-44 l'OO 



Manganese 0*42 



Alumina 0-21 



99-99 



The composition of this malacolite is, if 4 i per cent, of protox- 

 ide of iron are not taken into consideration, the same as those of 

 the first division. Before the blowpipe also, its properties are 

 completely like them. There occur, however, at Sahla other 

 kinds of sahlite, which, though similar in external appearance 

 to this, are quite different in their chemical properties and 

 composition ; while the sahlite just now described, and all 

 other malacolites of this composition, are easily fusible before 

 the blowpipe, these are almost entirely infusible ; and if reduced 

 powder, it merely agglutinates a little. In a small glass tube, 

 they blacken on the first action of the flame ; in the open 

 fire, they become white. 



The colour of these sahlites is the same as that of the be- 

 fore mentioned, but their lustre is much less, and so soft 

 that they are scratched by the nail ; while the other sahlite gives 

 sparks with steel. They occur in carbonate of lime, and are 

 usually penetrated by small veins of galena. The analysis of 

 these sahlites occasioned much trouble in ascertaining their true 

 nature. 



One of the purest specimens is in the collection of Prof. Ber- 

 zelius, who was kind enough to supply as much of it as 

 was sufficient for a chemical analysis. This sahlite, after having 

 been deprived by diluted nitric acid of calcareous spar, lost on 

 heating in different experiments 4*15, 4-92, 4*34, and 4-11 

 per cent, which distinguishes it sufficiently from the com- 

 mon malacolite, of which the loss in the fire never amounts to one 

 per cent.* 



The powder, after being heated, had a brown-red colour, and 

 gave the following results : 



* The hard sahlite lost in the fire 0'48 per cent ; the first variety of the malacolite 

 from Bjormyresoeden only 0-12; the second - 22 ; and the hedenbergite 0-7. This 

 latter mineral when heated in a small glass tube by the lamp of the glass blowers, 

 gives out a sour liquid which seems to contain fluoric acid. 



