]S 14. J Mineral called Hauyne. 195 



0-4705 gramme (7*26o' grains). Hence the whole diminution 

 amounted to 0*089 grain, or to 1*20 per cent. This loss must be 

 ascribed to water driven off by the heat. 



But as hauyne, when fused before the blow-pipe, forms a bead 

 filled with bubbles, it is obvious that it must contain a greater 

 quantity of water than this. 



B. 



a. — A quantity of hauyne of a slight greenish tint, to which 

 only a little mica adhered, was reduced in an agate mortar to a 

 very fine powder, which had a greenish white colour. 



b. — Of this powder 4*771 grammes (73*683 grains) were thrown 

 gradually into muriatic acid a little diluted. Immediately the 

 odour of sulphureted hydrogen gas was emitted, and paper dipped 

 in acetate of lead was stained black : yet no bubbles of this gas 

 could be seen separating from the powder. The first portions of 

 hauyne were slowly dissolved, giving the liquid a greenish colour, 

 and rendering it somewhat turbid ; but the last portions were 

 scarcely attacked. By the assistance of heat, however, the whole 

 was gradually and equally acted upon, and the liquid reduced to a 

 ielly of a greenish yellow colour ; which, however, was not trans- 

 parent, as Vauquelin says he observed it to be. 



This jelly, being gradually inspissated by a gentle heat, was 

 mixed with water, and then gradually evaporated to dryness. It 

 constituted a lemon yellow mass, which, when quite dry, assumed 

 a dirty white colour. This matter was again mixed with dilute 

 muriatic acid, boiled for a considerable time, new acid being con- 

 stantly added, and then reduced again to a dry powder. 



c — This powder was boiled in water acidulated with muriatic 

 acid for a quarter of an hour, and then the whole was passed 

 through a filter. The undissolved powder, being thus collected on 

 the filter, exhibited no traces of containing any of the mineral 

 unacted upon by the acid. 



d. — This powder, dried on the sand-bath, weighed 2"077 

 grammes (32077 grains). Of this 1 -6)^8 gramme, being exposed 

 to a strong red heat for half an hour, was reduced to 1*502 

 gramme. Hence the whole mass, if thus ignited, would have been 

 reduced to 1*848 gramme (2854 grains). 



e. — As the powder, when exposed to a red heat, split into 

 prisma, and as the quantity of silica thus found far surpassed what 

 Vauquelin had found in hauyne, 1 suspected that, notwithstanding 

 the long continued action of the muiiatic acid, a portion of alumina 

 might Mill adhere to this powder, and of course that it was not pure 

 lilica. Tliis suspicion was confirmed bv boiling in muriatic acid the 

 portion of the powder that had not been ignited. Alkalies, either 

 CUUStlC or carbonated, being dropped into this acid, threw down a 

 white powder, while muriate <>i barytcs 01 casioned no preeipilate. 



/. — Therefore I fused the whole of the ignited powder in a pla- 

 tinum crucible with caustic alkali, dissolved the fused mass by 



N 2 



