38 On some Mineral Substances before the Bloiopipe. [July, 



on cooling. In the reducing flame, the colour is a deep bottle- 

 green. 



With salt of phosphorus, the action is very slow and imperfect; 

 the globule is transparent, and, while hot, has a deep wine- 

 yellow colour.; when cold, it is colourless. In the reducing 

 flame the colour is lighter, and more inclined to green, while 

 hot ; when cold, colourless. A considerable portion of the 

 assay remains undissolved, in the form of a dark-grey silica 

 skeleton. 



2. Latrobite. (Phillips's Mineralogy, p. 380.) 

 Alone in the glass ??iatrass, at a red heat, gives off pure water ; 

 no decrepitation. 



Alone in forceps, fuses easily into a white enamel. 

 With soda, fuses into a semi-transparent, irregular globule, of 

 a light azure colour, when cold. The colour of the globule is not 

 uniform, spots of a deeper colour than the rest appearing scat- 

 tered over the surface. By the addition of nitre, the blue colour 

 is at first much exalted, and assumes a very slight greenish hue ; 

 but by long continued flaming, the blue colour disappears, and 

 is succeeded by a peach-blossom red colour, very similar to that 

 of the mineral. In the reducing fame, the colour is wholly 

 destroyed. 



With borax, dissolves very slowly, into a perfectly transpar- 

 ent, very light amethyst-coloured globule. In the reducing 

 fame, the colour entirely disappears. 



With salt of phosphorus, action slow, and solution imperfect; 

 globule transparent, very light-yellow, hot ; colourless and 

 slightly opaline, cold. In the reducing fame, the globule is 

 colourless and transparent, both hot and cold. An undissolved 

 silica skeleton remains in the globule. 



With nitrate of cobalt, the assay gives a fine blue colour, 

 intensely deep on the fused edges. 



By dissolving the soda globule in muriatic acid, &c. 1 

 obtained silica, alumina, lime, iron, and manganese. 



The latrobite is accompanied by a dark-coloured, nearly black 

 substance, dispersed through it, here and there, in minute 

 specks, which have an uneven, shining fracture, but are too 

 small to allow me to distinguish anything more of their external 

 characters. 



With salt of phosphorus, they presented before the oxidating 

 flame the phenomena detailed above, but in the reducing fame, 

 they gave a transparent glass, colourless while hot, and of a fine, 

 rather deep-amethyst colour when cold. This colour flies 

 instantly on the globule being heated, and on its cooling to a 

 certain point, returns as instantaneously. These dark specks, 

 therefore, appear to be an ore of titanium. 



I examined the mica, which is another concomitant of latro- 



