132 
CHEMICAL PRINCIPLES. 
Combinations 
of tellurium. 
which remained in the liquor not decomposed, had not changed 
its state of neutrality, except that it reddened the paper of lit- 
mus a little more after than before the infusion of the tellnrate 
of kali. The tellurale of lead, being well washed, forms a 
whitish powder. When healed, it loses its water of combina- 
tion, and becomes yellowish. At a temperature a little higher 
it melted and formed a mass semi-transparent, and resembling 
melted muriate of lead. Heated before the bellows on car- 
bon, this tellurate was reduced with a detonation, and formed 
tellure of lead. I caused two grammes of tellurate of lead 
to be dissolved in nitric acid, and into that solution poured sul- 
phate of natron, which precipitated sulphate of lead, which, 
being well w'ashed, and heated hot, weighed T477 gfs. The 
liquid, which still retained a little sulphate of lead, dissolved by 
the muriatic add, was precipitated by an addition of caustic 
kali, until the oxide of tellurium was re-dissolved, and there 
remained a sulphate of lead not dissolved, which, after being 
made red-hot, weighed 0'033 grs. Therefore, the whole of 
the sulphate of lead obtained from two grains of tellurate, 
was only 1'51 grs. in wdiich we found \ 5d grs. of oxide of 
lead. It follows, therefore, that the tellurate of lead was com- 
posed of 42 ?. pennyweights of oxide of tellurium, and of 5/ 3 
pennyweights of oxide of tin. The latter contains 4' 105 
parts of oxigen, while the former ccntains 6'4 grains, or 
X 135x2 = 6'?7 5 that is to say, that the oxide of tellurium 
contains twice as much oxigen as the base with which it was 
saturated. I have here called it oxide of tellurium, and not- 
withstanding it has operated as an acid in the analysed combi- 
nation, I have done so, because I do not think it right to give 
another name to the same substance. 
Telliirefum Hydrcgenii. 
Mr, Davy found, in his experiments cn this body, that the 
oxide of tellurium, precipitated by means of kali, always 
contains a considerable quantity of it, and that the metal which 
is obtained from it by this reduction, contains kaliuni. I have 
repeated this experiqaent, mixing tellurate of kali with carbon, 
and 
