296 Intelligence and Miscellaneous Articles. 



dicular to the axis of the prism are also evident, as well as those 

 which are parallel to the faces of the regular hexagonal prism. The 

 specific gravity of the mineral from New Jersey was 4" 154. 



By calcination, the silicate of zinc from New Jersey and the ville- 

 mite lose only 0-005 : this small loss is probably owing to a little 

 hygrometric moisture, and to the oxides of iron and manganese 

 which accompany both minerals ; the villemite becomes of a slight 

 brick-red colour. As to the New Jersey silicate, it has a brown 

 colour, a resinous lustre, and yields a powder of a light dirty green 

 colour, which becomes deeper by calcination : like villemite it is in- 

 fusible by the blowpijie ; with carbonate of soda on platina foil it 

 becomes green, indicating the presence of manganese ; in borax it 

 dissolves perfectly, with a sliglit colour indicating iron ; with phos- 

 phoric salt, a skeleton of silica remains in the globule. 



The silicate of zinc from New Jersey, like villemite, is very easily 

 acted upon by hydrochloric acid, and the silica separates in the ge- 

 latinous state ; it then produces an incrustation around the central 

 part, and it is necessary to continue the ebullition for some time, 

 that the action may be complete. 



For a quantitative analysis about fifteen grains were dissolved in 

 hydrochloric acid ; after having sejiraateil the silica in the usual way, 

 the liquor was evaporated a second time, by which a little more was 

 obtained ; the zinc was separated by solution in potash, by repeatedly 

 treating the residue insoluble in acid : the iron was separated from 

 the manganese by succinate of ammonia ; no cadmium was detected. 



There were by these means obtained, by the analysis of the ville- 

 mite of Vieille-Montagne and the silicate of ziuc from New Jersey 

 the following results : — 



Vieille-Montagne. 



Silica 27-28 



Oxide of zinc ' 72-37 



Protoxide of iron 0-35 



100-00 

 New Jersey. 



Silica 27-40 



Oxide of zinc 68-83 



Protoxide of manganese 2-90 



Protoxide of iron 0*87 



100-00 

 The results of these analyses agree very well with those of ville- 

 mite and silicate by MM. Thomson, Levy, Vanuxem and Keating. 

 It follows that manganeseous silicate of zinc of New Jersey, and the 

 villemite, though at first presenting different appearances, belong to 

 the same mineral species, which is a tribasic silicate of zinc Si Zn^ ; 

 or supposing that silica contains only two atoms of oxygen, they will 

 be bibasic silicates of zinc Si Zn". — Ann. des Mines, tome x. 1846. 



