78 Intelligence and Miscellaneous Articles. 



form is irregular, but in some cases it has the appearance of six- 

 sided tables, which approach a regular form ; these scales are raven- 

 black, and reflect a very bright green, and yield a green powder. 

 Separately examined they are flat and shining, their lustre is vitreous 

 like the diamond, with very brilliant aggregated faces. They are not 

 translucent, but when very small they are transparent. It is dlflfi- 

 cult to state their cleavage and flexibility ; their specific gravity is 

 3- ; hardness on Mohs's scale =3. It is therefore harder than 

 the mica of two axes, but less so than the pearly mica ; it is rather 

 brittle ; it is rather hard to the touch, but less than pearly mica. 

 Heated to redness by the blowpipe, it becomes of a tombac brown 

 colour, with the metallic lustre of magnetic iron ore. It gives a 

 bottle-green colour to borax, dissolves readily in nitric and hy- 

 drochloric acid, and the silica remains in soft pearly scales and ciy- 

 stalline form, like the mica of one axis. It yielded by analysis 



Silica 37-40 



Alumina 11'60 



Oxide of iron 27-66 



Protoxide of iron 12-43 



Magnesia and lime 0-60 



Potash 9-20 



Water 0-60 



99-49 

 In some of its characters this mineral resembles a species of mica 

 which M. Breithaupt has described under the name of Sideriscker 

 Felsglimmer, or Raben Glimmer ; but as the analysis of this has 

 not been given, it is difficult to ascertain whether these two minerals 

 belong to the same mineral species. — L'Institut, No. 352. 



HYDROTELLURIC ^THER. BY M. F. WOHLER. 



The existence of this compound is interesting, as aff'ording a fresh 

 proof of the remarkable analogy which exists between sulphur and 

 tellurium, and as showing that the latter substance may, like sul- 

 phur, enter into the composition of organic compounds, and replace 

 oxygen in them. 



This sether is readily prepared by the double decomposition of 

 sulphovinate of barytes and telluret of sodium ; it is sufficient for 

 this purpose to submit solutions of these two substances in water to 

 distillation. The telluret is prepared by the calcination of tellurium, 

 or the native telluret of bismuth with carbonate of soda, mixed with 

 charcoal ; and, in order to avoid oxidation, the rough product is im- 

 mediately conveyed to the retort which contains the boiling solution 

 of sulphovinate. The hydrotelluric jether distils with the water, 

 yielding, at the beginning, much froth in the retort. 



This substance is a liquid of a reddish-yellow odour, approaching 

 the colour of bromine, but lighter ; it is heavier than water, and this 

 dissolves only a trace of it; its odour is disagreeable, extremely 

 penetrating, and remains for a long time; it partakes of the smell 

 both of hydrosulphuric ajther and hydrotelluric acid, and it appears 



