Scientific Intelligence. — Mineralogy . 189 
selenium. It was found some years since in the St Lawrence 
mine near Clausthal ; and M. Bauersachs, who, at that time, 
regarded it as a distinct species, termed it Cobaltic Galena, under 
which name Professor Hausmann introduced it into his Minera- 
logy. The mineral ogical description of it, as given by Profes- 
sor Hausmann, is as follows : Externally it bears considerable 
resemblance to fine-granular galena, though its colour is clearly 
different, having a cast of blue like molybdena. A crystalline 
texture is quite distinct, but, from the minuteness of its crystals, 
it has hitherto been impossible to ascertain their precise form. 
Cubic and triangular surfaces were observed ; but whether they 
correspond or not to those of galena, could not be determined. 
A similar remark applies to its cleavages, of which there appear 
to be several. It is less hard than galena, and its density is 
7.697. It becomes negatively electric from friction, like galena. 
It is readily decomposed, before the blowpipe, on charcoal. Be- 
sides the usual phenomena, arising from the presence of lead, 
the odour of decayed horse-radish may be perceived ; and a red- 
dish-brown matter is deposited round the assay on the cool 
parts of the charcoal. The ore shines wdth a clear blue light, 
while the blowpipe flame is playing upon it. It communicates 
a pale blue colour to borax, indicative of a little cobalt. When 
heated by means of a spirit-lamp, in a clear glass-tube, closed 
at one end, the selenium almost instantly sublimes, form- 
ing a red ring within the tube, at the open extremity of which 
its peculiar odour is very perceptible. On heating the tube to 
redness, the ore fuses, the red ring partially disappears, and is 
succeeded by a white crystalline deposit. This deposit reddens 
litmus paper, is deliquescent, and has all the properties of se- 
lenic acid. These characters, which I have myself witnessed on 
a specimen sent me by Professor Stromeyer, are very distinct. 
Nitric acid acts readily upon the ore even in the cold. The 
lead is first attacked, the selenium separating in substance in red 
flocculi ; by the aid of the heat these also are oxidized, selenic 
acid being generated. The solution, when complete, has a pale 
rose colour, owing to the presence of cobalt ; but the nicest test 
could detect neither sulphuric acid, nor any other substance. 
The analysis was performed by the following method : After 
dissolving the ore completely in nitric acid, the oxide of lead was 
