348 Intelligence and Miscellanecms Articles. 



With borax, M. Ebelmen formerly obtained microscopic crystals 

 of alumina ; the addition of a substance which gives a somewhat more 

 difficult fusibility to the flux, as carbonate of baryta or silica, caused 

 the production of beautiful crystals of alumina of the most si)lendid 

 lustre. These crystals had the form of a six-sided double pyramid, 

 appearing very considerably truncated on both summits, so tliat they 

 resembled the strongly flattened plates of iron-glance of the volcanoes. 

 The measurement of the angle between the lateral facets and the 

 base showed that it was identical with those of corundum. This 

 artificial corundum scratched quartz and topaz easily. 



By using the phosphates as solvent, tantalic, niobic, and titanic 

 ncids were obtained in crystals. Titanic acid crystallizes from the 

 phosphate in long needles, the specific gravity of which is =4*283, 

 hence identical with rutile. 



All the artificial crystals which the author obtained have been 

 optically examined by him, and found, with the exception of those 

 belonging to the regular system, to exhibit the action upon polarized 

 light. — Comptes Rendus, vol. xxxii. p. 330-333. 



FURTHER RESEARCHES UPON CRYSTALLIZATION BY THE DRY ME- 

 THOD. BY M. EBELMEN. 



In my former investigations, I employed as solvents for the ele- 

 ments various fluxes which are volatile at high temperatures, such 

 as boracic acid, borax, and acid and alkaline phosphates. It struck 

 me that some new series of compounds might be obtained by using 

 alkaline instead of acid fluxes, such as the carbonates of potash and 

 soda, which are so frequently employed in mineral analyses for dis- 

 solving by the dry method those substances which are not acted 

 upon by acids. These substances, like boracic acid, possess the 

 double property of assuming the liquid state at temperatures easily 

 produced in our furnaces, of dissolving a large number of metallic 

 oxides, and of becoming completely volatilized in open vessels at a 

 temperature slightly above that at which they undergo fusion. 



When a mixture of silica and magnesia, in such proportions as to 

 constitute the bisilicate, is exposed to a high temperature with bi- 

 carbonate of potash, after the lapse of some days we obtain a per- 

 fectly liquid vitreous mass, at the bottom of which very transparent 

 colourless crystals are formed. These are easily separated from the 

 fused mass, by treating it with very weak acids and solution of 

 potash, whtch dissolves the glass without acting upon the crystals. 

 They are easily recognized as peridote. I have succeeded in mea- 

 suring their angles. The facet g' is well-marked ; the other facets 

 which I have detected are those of e^, e\ g^. A', and a! ; the measured 

 angles differ scarcely a few minutes from those which have been 

 obtained with the natural crystals. 



It is evident that in this reaction half the silica separates to form 

 an infusible combination with the magnesia ; the vitreous matter 

 acted upon by acids also contains magnesia ; a great part of the pot- 

 ash was volatilized. Titanate of lime, TiO CaO, may be obtained 



