186 Dr. Walchner's Mineralogical and Chemical 



nesia was present, and the solution was carefully neutralized 

 with carbonate of soda. Perhydrate of iron was separated, 

 which was treated with caustic potassa and then separated by 

 filtration from the alkaline fluid, from which muriate of am- 

 monia precipitated a little alumina. The solution, from which 

 iron and argillaceous earth had thus been separated, was 

 mixed, at a boiling heat, with carbonate of soda. The co- 

 pious precipitate thus obtained consisted of magnesia, which, 

 after desiccation and exposure to a red-heat, and re-solution 

 in dilute nitric acid, yielded a little oxide of manganese. 

 The neutralized solution of magnesia in nitric acid became 

 turbid, but in a scarcely perceptible degree, by the addition 

 of oxalate of ammonia. 



b.) A second portion of the mineral was treated with 

 muriatic acid, in order to ascertain the alkali which it 

 might contain : the solution was evaporated to dryness, the 

 silica separated in the usual manner, and the fluid remaining 

 after the separation of the silica precipitated with caustic am- 

 monia and with its carbonate. The residuum obtained by 

 evaporation, was ignited in a platinum crucible, in which mu- 

 riate of potassa remained. 



It will be seen from these experiments that the hyalosiderite 

 consists of silica, oxide of iron, magnesia, alumina, oxide of 

 manganese, and potassa. 



§ 10. A. 



In order to determine the proportions of the constituent 

 parts of this mineral, it was subjected to the following analysis : 



a.) 1 '040 gramm. of hyalosiderite, reduced to the finest pow- 

 der, were exposed to a moderate red-heat for about half an 

 hour in a platinum crucible, with three times its weight of 

 anhydrous carbonate of soda. The mixture, after fusion, 

 was of a brownish-yellow colour, and gave, when softened 

 with water and treated with concentrated muriatic acid, a 

 clear yellow solution. By evaporation to dryness &c. 0*329 

 of calcined siliceous earth were obtained. 



b.) After the separation of the silica, the remaining fluid 

 was accurately neutralized with carbonate of soda. The pre- 

 cipitate thereby occasioned, after having been separated from 

 the fluid, was digested, whilst yet in its moist state, with a so- 

 lution of caustic potassa, so long as it became diminished in 

 quantity ; and the residual iron well dried and calcined gave 

 0*330 gramm. of peroxide of iron, =0*309 protoxide of iron. 



c.) The alkaline fluid of (b) was now treated with a solu- 

 tion of muriate of ammonia so long as precipitation took place. 



This 



