398 Intelligence and Miscellaneous Articles. 
Demidovite occurs upon the mammillated masses of malachite in 
layers of at the utmost 1 or 2 millimetres in thickness; sometimes 
several of these layers are seen alternating with malachite and Ta- 
guilite, and other phosphatic minerals. Between the Demidovite and 
the malachite there is often a very thin white layer, either composed 
of pure silica, or of silica mixed with white carbonate of copper*. 
The external surface, where it has not been covered by malachite, 
is tolerably shining, but uneven and full of little clefts in different 
directions, scarcely visible by the naked eye. 
It is of a sky-blue colour, sometimes passing a little into greenish. 
Its fracture is dull, or of a waxy lustre. 
It is transparent only at the edges, but becomes more so when 
placed in water. It is so porous that it adheres to the tongue. 
Brittle. 
Hardness nearly the same as that of gypsum. 
When scratched it yields a white powder. 
Its specific gravity is about 2°25. 
Before the blowpipe it becomes black in the oxidizing flame ; in 
the inner flame it fuses readily, and furnishes a black scoria, acqui- 
ring a metallic lustre on the surface. In a glass tube closed at one 
end it becomes black and furnishes water, which presents no trace 
of acid if the fragments be clean. 
With borax it fuses readily, and without swelling, in the outer 
flame, furnishing a glass which is at first black, and acquires a bluish- 
green colour in cooling: in the inner flame the globule becomes 
nearly colourless, in consequence of the reduction of the copper. 
Every time that the globule is heated afresh, a greenish flame is seen ; 
this no longer appears when the heat is continued. 
With salt of phosphorus a yellow colour is obtained as long as the 
globule is warm; after cooling, it has the same colour as with borax, 
but the fragment leaves a skeleton of silica. The globule cannot 
be decolorized in the inner flame. 
When fused for a long time with boracic acid into which an iron 
wire has been introduced, the wire dilates a little and acquires a 
very pale copper colour; the iron nevertheless remains malleable. 
With a little soda it fuses and gives a black glass; if the quantity 
of soda be increased, the copper is reduced, but it requires a large 
amount of soda to cause the scoria to enter the charcoal. The cop- 
per obtained is a little paler than that procured by employing red 
copper. 
In the laboratory which I was able to establish at Taguil, I made 
an analysis of this mineral, from which I saw that it possessed a new 
composition. Ido not, however, regard the analysis as perfectly 
satisfactory with regard to the proportions of the substances of which 
it is composed ; because, as I was only able to collect a very small 
quantity of the mineral in a state of perfect purity, I was obliged to 
operate upon very small quantities. 
After having, by preliminary experiments, ascertained the presence 
* An artificial compound of carbonate of copper of a white colour has 
been investigated by M. H. Struve of St. Petersburgh. 
