EXPERIMENTS ON THE METALS FROM THE FIXED ALKALIS. ^33 



off, a vivid light appeared in the retort, and there was found Accidental al- 



in it the alloy of tellurium and potassium. la 7 of ,dlliriu ^ 



\ * t with potassium , 



In attempting to reduce somi* oxide of tellurium by char- 

 coal, which Mr. Hatchett had the kindness to give me for 

 the purposes of these experiments, and which must haye 

 been precipitated by potash, or from a solution in potash, I 

 found, that a sufficient quantity of alkali adhered to it, even 

 after it had been well washed, to produce an alloy of potas- 

 sium and tellurium ; but in this alloy the potassium was in 

 very small quantity. It was of a steel gray colour, very 

 brittle, and much more fusible than tellurium. 



I shall not arrest the progress of discussion, by entering Aeriform com- 

 at present into a minute detail of the properties of the hniumaudfai- 

 aeriform compound of tellurium and hidrogen ; I shall drogen. 

 mention merely some of its most remarkable qualities and 

 agencies, which, as will be shown towards the close of this 

 paper, tend to elucidate many points immediately connected 

 with the subject in question. The compound of tellurium 

 aud hidrogen is more analogous to sulphuretted hidrogen, 

 than to any other body. The smell of the two substances 

 is almost precisely the same*. Its aqueous solution is of a 

 claret colour; but it soon becomes brown, and deposits 

 tellurium, by exposure to air. When disengaged from 

 an alkaline solution by muriatic acid, it reddens moistened 



* In some experiment?, made on the action of tellurium and Supposition, 



potassium, in the laboratory of my friend John George Children that telluriu . m 



, ° . misrnt contain 



iisq., of Tunbridge, in which Mr.Children,.Mr. Pepys, and Mr. War-sulphur, 

 burton cooperated; the analogy between the two substances struck 

 us so forcibly, as for some time to induce us to conceive, that tel- 

 lurium might contain sulphur, not manifested in any other way 

 but by the action of voltaic electricity, or of potassium; and some 

 researches made upon the habitudes of different metallic sulphurets, 

 at the voltaic negative surface, rather confirmed the suspicion ; for 

 most of the sulphurets that we tried, which were conductors of 

 electricity, absorbed hidrogen in the voltaic circuit. The great im- 

 probability, however, of the circumstance that sulphuric acid, or 

 sulphur in any state of oxigenation, could exist in a metallic solu- 

 lution, which was not manifested by the action of barytes, induced 

 me to resist the inference ; and farther researches, made in the 

 laboratory of the Royal Institution, proved, that the substance in 

 'question was a new and singular combination. 



litmus 



