Page:Proceedings of the Royal Society of London Vol 1.djvu/340

Rh plied, neither potash nor ammonia can be produced; and if oxygen merely be applied, potash and nitrogen are the result.

In consequence of the supposition of Messrs. Gay-Lussac and The- nard, that they had formed a compound of potassium and hydrogen, Mr. Davy repeated their experiment frequently, without any success; neither has he, by any other means, been able to form a compound of hydrogen with potassium.

In the residuum obtained by heat, after the action of potassium on ammonia, the nitrogen appears to be combined with an oxide of po— tassium, in which the oxygen amounts to about three per cent. By greater heat this compound itself sublimes, and does not yield nitro- gen Without the intervention of oxygen; as if some portion of the latter were essential to the constitution of nitrogen gas.

Mr. Davy refers to an hypothesis formerly advanced, that all me- tals may possibly be compounds of unknown bases with hydrogen; but replies to those arguments by which Messrs. Gay-Lussac and Thenard imagined that they had proved the existence of hydrogen in potassium; forwhich there appears to be no foundation in fact. Un- til hydrogen can be separated from some metallic substance,—until a metal can be deprived of its imﬂammability by the separation of hy- drogen, that theory must be preferred, which, in explaining all the facts, admits the presence of no ponderable agents of which the ex- istence cannot be proved.

Mr. Davy next proceeds to an examination of sulphur, ﬁrst by passing discharges through it in a ﬂuid state from a common electric machine, but afterwards with better success by the voltaic battery, and obtained gas from it in sufﬁcient quantity to ascertain that the gas consists Wholly of sulphuretted hydrogen. In the course of the process, the sulphur had acquired the power of reddening litmus. After long—continued electrization, the sulphur became extremely dif- ﬁcult of fusion and acquired a dirty brown colour.

By the action of potassium on sulphur, sulphuretted hydrogen is also evolved with intense heat and light; and the circumstances of this operation appear tobe similar to what occurs when potassium is heated in contact with resin, camphor, wax, and ﬁxed oils, in close vessels. For in this case also, great heat is generated, and great quantities of carburetted hydrogen evolved. In addition to this analogy in their chemical actions, Mr. Davy also remarks, that the physical qualities_of these bodies resemble those of sulphur.

They agree in being non-conductors, whether ﬂuid or solid; transparent when ﬂuid, but semi-transparent when solid, and highly refractive; but resinous and oily bodies contain a small quantity of hydrogen and oxygen, With a large quantity of carbonaceous matter. So also in sulphur, the mixture of hydrogen is fully proved, and the existence of oxygen might be inferred from the effect of the residual sulphur on litmus paper, but is more distinctly evinced by the formation of potash when potassium is heated in sulphuretted hydrogen. From such experiments as were most to be depended upon, it