Intelligence and Miscellaneous Articles. 151 



the following characters : it has the form of small crystalline laminae, 

 usually radiating from a centre ; it is sometimes separated from dis- 

 thene by a thin stratum of yellowish oxide of iron, evidently result- 

 ing either from the recent decomposition of disthene, or of the rock 

 in which it occurs. In fragments, the substance is yellowish- whife, 

 and translucent ; is cut by the knife, and formed by the agglomera- 

 tion of a multitude of small lamina 3 , indicating a radiated structure ; 

 these laminae are perfectly transparent, but have no crystalline form. 

 The cohesion of this substance is slight, but still it is difficult to 

 reduce it to a fine powder. When pulverized it has the appearance 

 of small scales of a shining silvery- white colour, with a pearly lustre ; 

 it is soft to the touch, but not unctuous like talc ; it is harder than 

 talc, for it scratches it ; but it is not so hard as fluor spar ; its den- 

 sity is 2'792; after drying at 212° and heated in a tube, it yields 

 water ; when dried over sulphuric acid in vacuo, it loses only a few 

 thousandths of its weight, and retains its water, which is conse- 

 quently in a state of combination ; heated on platina it swells and 

 becomes milk-white ; when more strongly heated, it agglutinates and 

 then fuses, but with difficulty, into a white enamel ; it is phospho- 

 rescent and emits a brilliant light ; with nitrate of cobalt it becomes 

 of a pure blue colour, when strongly heated ; with borax it dissolves 

 readily and perfectly, with a slight colour proceeding from iron ; with 

 the salt of phosphorus it yields a colourless crystalline bead ; the so- 

 lution is quite complete, no silica skeleton remaining ; with carbonate 

 of soda effervescence ensues ; alumina is left unacted upon, even when 

 excess of the carbonate is employed. 



Neither hydrochloric acid nor aqua regia acts upon this substance, 

 but when finely levigated and boiled with concentrated sulphuric 

 acid, it is completely decomposed ; the silica remains in the granular 

 state and retains the form of the scales. After calcination, it is not 

 acted upon by the acid. 



The qualitative analysis of this substance shows that it contains 

 silica, alumina, a little iron and manganese, the last two not appear- 

 ing to be in a state of combination, potash and water ; soda was not 

 found to be present, which it is proper to state, for usually the two 

 alkalies occur together. As the mineral possesses some of the cha- 

 racters of mica, fluorine was sought for but not found. 



In determining the quantity of water, it was found requisite to 

 heat it pretty strongly to separate the whole of it ; when only a part 

 of it was expelled, it was found that on placing it in water for some 

 days and then drying it by exposure to the air, it regained exactly as 

 much water as it had lost ; when however it is strongly heated and 

 loses all the water, it does not regain it by immersion. 



Analysed by means of nitrate of barytes, this substance yielded — 



Silica 45-48 



Alumina. . . . 38-20 



Potash 11-20 



Water 5-24 



100-12 

 with traces of iron and manganese. 



