1820.] Scientific Intelligence. 147 



be so far correct that the primitive form of the crystals is the 

 same in both. At the same time there is a considerable differ- 

 ence in the appearance of the two minerals, and hkewise in the 

 chemical composition, though this last may be owing to 

 foreign matter with whicli the Egeran is always contaminated. 

 Its specific gravity is 3*294. The following table exhibits the 

 constituents of Egeran, as determined by the analysis of Count 

 Borkowski : 



Silica 41 



Alumina 22 



Lime 22 



Magnesia 3 



Iron 6 



Manganese 2 



Potash 1 



97 

 (Schweigger's Journal, xxiii. 387.) 



Idocrase, according to the analysis of Klaproth, is composed 

 as follows : 



SiHca 83-50 



Alumina 22-25 



Lime 33-00 



Oxide of iron 7-50 



Oxide of manganese 0-25 



98-50 



So that Egeran contains less silica and more lime than idocrase. 

 But if a mineral from Siberia, which Klaproth considered as art 

 idocrase, was really one, as there is every reason, from his 

 description of it, to conclude, then the composition of idocmse 

 and Egeran is more nearly the same. Klaproth found the com- 

 position of the Siberian mineral as follows : 



Sihca 42-00 



Alumina 16-25 



Lime 34-00 



Oxide of iron 5-50 



Oxide of manganese Trace 



97-75 



The specific gravity of the Siberian mineral was 3-365 — 

 3-o90. its colour was dark olive-green. The crystals were 

 rectangular four-sided prisms, with the edges sometimes so 

 much truncated that thay assumed the appeaiance of eight-sided 

 prisms. 



III. New Nickel Ore. 

 Cronstedt made known a new nickel ore found at Iltlsing, iu 



k2 



