examined bij the Bloxc-Pipc. 31 1 



a mass. The soda sinks into the charcoal without the oxide 

 of sine being condensed on its surface. With cobalt volution 

 a greenish colour is produced. 



The Siliceo-Carbonate of Zinc, from Aachen, is crys- 

 tallized. Alone, in a matrass, it affords nitre and carbonic- 

 acid, and falls to pieces without fusing. 



With salt of phosphorus it decomposes with difficulty. A 

 skeleton of silica is distinctly seen before the glass is cold; it 

 turns opaque in cooling, and deposits a ring of zinc fumes. 

 With borax it comports itself like the carbonate ; with soda, a 

 half melted scoria is produced, along with a great quantity of 

 zinc fumes; with solution of cobalt, it produces a blueish 

 colour on the edges. 



Siliceo-Carbonate of Zinc, Derbyshire. This mineral 

 occurs in clear prismatic crystals. Alone, in a matrass, it de- 

 crepitates, gives off carbonic acid, and but a very minute por- 

 tion of water. In a strong heat it melts only on the edges. 

 With salt of phosphorus it melts with facility ; the glass does 

 not become opaque, in combination with so small a quantity as 

 the former. No skeleton of silica is to be seen. 



Cupreous Silicate of Zinc, Siberia. This is a combi- 

 nation of two minerals. The specimen consists of two distinct 

 layers ; the upper one is colourless, and comports itself like the 

 siliceo-carbonate of Aachen. The under layer exposed to heat in 

 the matrass, affords nitre and carbonic acid. On charcoal it 

 turns black, and melts slightly on the edges, and communi- 

 cates a green tint to the flame ; with salt of pliosphorus it 

 •rives a glass which exhibits the colour of copper. A small 

 metallic globule, generates on the side of the array, which, as 

 the glass cools, spreads itself over the surface, and gives it 

 a white metallic lustre. 



Siliceo-Carbonate of Zinc and Iron, Siberia. — This 

 mineral turns black in the matrass, falls to pieces, yields car- 

 bonic acid and a little water, and becomes magnetic ; icith 

 salt of phosphorus, it decomposes easily, leaves a skeleton of 

 silica, and tinges the glass the colour of iron ; is opaque on 

 cooling, and leaves a white ring of zinc fumes ; with borax. 

 produces a glass coloured with iron ; with soda, a brownish 

 half melted scoria. This mineral has been improperly named 

 a silicate of zinc. 



