Intelligence and Miscellaneous Articles. 315 



their form is a square prism, and often the regular octagonal prism. 

 It scratches glass feebly. Specific gravity 2'95. 



Chemical characters. — When heated in a tube no water is ob- 

 tained. By the blowpipe becomes a pale yellowish glass, if the 

 crystals be slightly coloured, but a black glass if brown crystals be 

 used. This glass is sometimes attracted by the magnet, but this 

 property is not constant with all of the products. When fused with 

 borax on a small white cupel, melilite dissolves entirely ; if a little 

 nitre be added the fused matter has a brown colour while it is hot, 

 but on cooling it assumes a slight rose tint, indicating the presence 

 of manganese ; this the pale crystals do not exhibit. Salt of phos- 

 phorus dissolves it partially, leaving a skeleton of silica. Hydro- 

 chloric acid dissolves it readily, gelatinizing, and becoming of a 

 yellow brown colour. 



By some preliminary trials M. Damour ascertained that melilite is 

 composed of silica, alumina, peroxide of iron, with a considerable 

 quantity of lime, a little magnesia, potash, soda, and traces of oxide 

 of manganese. 



To discover the state of oxidizement of the iron, sodio- chloride of 

 gold was added to the hydrochloric solution of the mineral, placed 

 at the bottom of a bottle, hermetically sealed, and previously filled 

 with carbonic acid gas ; no trace of reduced gold was perceptible, 

 whence it was concluded that the iron was in the state of peroxide, 

 a conclusion which was strengthened by also employing the method 

 described by Berthier in the second volume of the Annates des Mines, 

 1842. M. Damour tried in vain to detect the titanic acid mentioned 

 by M. Carpe. 



For the two analyses which M. Damour made of this substance, 

 crystals were selected which were well separated from the gangue ; 

 but they contained small grains of pyroxene, and other matters, which 

 resisted the action of hydrochloric acid. 



Quantitative analysis. — The mineral reduced to coarse powder and 

 dried was acted upon by hydrochloric acid. The silica, separated 

 by the usual processes and weighed, was afterwards treated with a 

 solution of potash, to separate the insoluble matters ; in each opera- 

 tion there remained about 4 per cent, of small crystalline grains, 

 which was deducted from the total weight of the substance employed, 

 and from that of the silica. 



The acid solution containing the bases separated from the silica 

 was neutralized by ammonia ; peroxide of iron and alumina were 

 precipitated, carrying down a little lime and magnesia ; these oxides 

 after washing and calcining were weighed. In order to separate the 

 peroxide of iron from the alumina, they were digested in hydro- 

 chloric acid ; the greater portion of the oxide of iron was dissolved, 

 but there remained a yellowish insoluble powder, greatly resembling 

 impure titanic acid, and this was fused with bisulphate of soda ; the 

 fused mass was entirely dissolved by boiling water, and the solution 

 was added to the hydrochloric solution containing peroxide of iron ; 

 by means of excess of potash the alumina was separated from the 

 peroxide of iron ; the alkaline solution, separated from the precipi- 

 tated peroxide of iron, was supersaturated with hydrochloric acid, 



