ISO 
CHEMICAL PRINCIPLES. 
Combination: 
of telluritiiu. 
i I found this piece did not contain any foreign metal. I 
csused it to be dissolved in tlie nitric acid in a phial correctly 
weighed : I afterwards caused the acid to be evaporated, and 
I heated the residue gently, until it would give out no rhore 
nitrous vapour. There then remained in the phial 3 JA5 grs. 
of oxide of tellurium j that is to say, 100 parts of this metal, 
combined with 24'63 parts of oxigen. The oxide of tellurium 
is volatile j if it is too much heated, it begins to sublimate, and 
if any cold body be introduced into the phial on which it is 
heated, the latter will be immediately covered with a white 
sublimate. The oxide of tellurium is easily melted, and after- 
wards, when it grows cold, takes a yellowish colour, and has 
a crystalline texture. Heated on a bit of carbon before a bel- 
lows, it becomes, first of a citron colour, then orange, and 
lastly, a fine red : it then melts and enters the carbon, where 
it is consumed, with an effervescence, forming a small greenish 
'flame. 
The oxide of tellurium, which has been fused, docs not re- 
act on paper of litmus. It requires considerable digestion to 
dissolve it in the nitric acid, and by which it will not be 
carried to a higher degree of oxidation. With the sulphuric, 
nitric, and muriatic acids, it forms salts as neutral as those formed 
with acids, for the most part with other metals. The muriat 
is decomposed in part, when treated with much water, which 
precipitates a sub-muriat, but the latter, notwithstanding its 
evident base, has the property to turn turnsol very red. The 
nitrate of tellurium, decomposed to a moderate heat, until 
most of the acid is driven out, affords a while powiier, which, 
beii.g well washed with water, re-acts as an acid, exactly as 
we see it happens with oxides of antimony, tin, and, like those, 
the oxide of tellurium loses that property on being exposed to 
fire. 
If oxide of tellurium is mixed with saltpetre, and then ex- 
posed to the fire, the nitrate of potash at first melts, without 
acting on the oxide j but at the temperature at which the 
latter begins to liquify, it deCompo.ses the nitrate with a violent 
i.-ffervescencc, the nitric acid is then driven out, and the oxide 
of 
