230 Scientific Notices — Mineralogy. [March, 



scissars), with two parts of caustic potash, for half an hour, and 

 digested the mass in 100 parts of water. Muriatic acid was 

 gradually added to the mixture till it was slightly in excess ; th6 

 solution evaporated slowly to dryness ; the residuum washed 

 with cold water, and the silica separated by the filter. /;*"'♦■' 



If the siHca was coloured, which often happened, he digested 

 it in cold muriatic acid diluted with 10 parts of water, till it 

 became white ; it was then washed, and while still moist boiled 

 in strong muriatic acid. The liquid was then evaporated to 

 expel the greater part of the acid, diluted and filtered , and the 

 solution, containing only a slight excess of acid, treated with an 

 infusion of galls. If titanium was present the solution first 

 assumed a yellowish red colour, and soon afterwards tannate of 

 titanium separated in flakes of the same colour. 



The muriate of titanium is so easily decomposed by heat, that 

 in general the greater part of the metal is found with the silica, 

 which should always be carefully examined in all analyses in 

 which titanium may be expected to be discovered. If, on the 

 other hand, the evaporation have not been carried far enough, a 

 portion may remain in solution in the washings of the silica. To 

 be certain, precipitate the solution by ammonia, wash the preci • 

 pitate, and digest it in caustic potash, which will dissolve the 

 alumina, and tlie oxide of titanium, and the latter may then be 

 separated by saturating the alkali with muriatic a«id, and preci- 

 pitation by infusion of galls. 



Nearly two years since, I examined a dark brown mica, from 

 Siberia, for titanium, without finding the least trace of that 

 metal. — C. 



MlNEUALOGY. 



3. Harmotome. 



Dr. Wernekinck, of Giessen, has published a description and 

 analysis of a new variety of this mineral in which the barytes is 

 replaced by lime. Its constituents, according to his analysis, 

 are : 



Silica 53-07 



Alumina 21'31 



' Lime 6"67 



Barytes 0-39 



Oxides of iron and manganese 0*56 



Water 17-09 



99-09 



It is found in a basaltic amygdaloid, near the village of Anne- 

 rode, at the distance of about a mile from Giessen.- It always 

 occurs in regular crystals, and the only crystalline form under 

 which it has been hitherto observed is a perfect square prism, 



