C. Thompson

I. On certain ternary alloys. Part II

In Part I, it has been shown that when the three metals lead, zinc, and tin are fused together and well intermixed, and the mixture allowed to stand molten for some hours at a nearly constant temperature, a single homogeneous alloy results if the proportion of tin present exceeds a certain lim iting amount (about three-eighths of the entire mass); but with smaller proportions of tin the mass divides itself into two different ternary alloys of unequal density: the heavier contains chiefly lead, together with some of the tin, and as much zinc as the lead can dissolve in presence of the particular proportion of tin associated with it; whilst the lighter mainly consists of zinc, with the rest of the tin, and as much lead as the zinc can dissolve in presence of that tin. We have found that analogous results are obtained with various other ternary mixtures of metals, A, B, C, such that whilst A and B are not miscible together in all proportions (like lead and zinc), C is miscible in all proportions w ith either A or B separately. Of such mixtures, the following are example.

XVII. Note on the development of voltaic electricity by atmospheric oxidation of combustible gases and other substances

About fourteen months ago we had the honour of communicating to the Society (‘Roy. Soc. Proc.,’ vol. 44, p. 182) the results of a large number of experiments made with electromotor cells, of which a special feature was that one of the plates of the combination consisted of an “aeration plate,” or layer of conducting material exposed to the atmosphere, and consequently superficially charged with a film of condensed air, which served as a means of indirectly effecting the oxidation of the other plate (when made of oxidisable metal), or of the fluid surrounding it (when the plate is of non-oxidisable material immersed in an oxidisable fluid). We showed that the E. M. F. of a given combination varies very considerably with the nature of the material of which the aeration plate is made, surfaces of platinum sponge, and especially platinum black, yielding the highest results when the electrolyte is dilute sulphuric acid; a convenient way of constructing the plates being to apply the spongy metal to the surface of unglazed earthenware, or other similar porous non-conducting material, so as to form a conducting film, the electrolytic fluid being absorbed in the porous material and so making contact.

III. On certain ternary alloys. I. Alloys of lead, tin, and zinc

It is well known, that quite apart from a tendency to separate more or less completely into different mixtures during solidification, certain mixtures of molten metals show a tendency to separate into two alloys of different densities on standing fused for some time.

On the voltaic circles producible by the mutual neutralisation of acid and alkaline fluids, and on various related forms of electromotors

The authors have examined a variety of cells analogous to Becquerel’s “pile à oxygène;” i. e., containing two platinum or other non-oxidisable plates, one immersed in an acid fluid, the other in an alkaline one, the two fluids being connected by a wet wick or siphon, and either some oxidising agent being also contained in the acid or some reducing substance in the alkali. In the first case continuous evolution of oxygen was brought about from the surface of the plate immersed in the alkali; in the second the converse phenomenon was observed, i. e., hydrogen was continuously evolved from the plate in the acid; in each case the quantity of gas liberated was equivalent to the current passing as measured by a small silver voltameter.

I. Note on the development of feeble currents by purely physical action, and on the oxidation under voltaic influences of metals not ordinarily regarded as spontaneously oxidisable

In the course of a series of further experiments on cells set up with “aeration plates” (plates simultaneously in contact with the air and the electrolytic fluid used in the cells—‘Roy. Soc. Proc.,’ vol. 42, p. 212), we have made a large number of determinations of the E. M. Fs. developed with incorrodible aeration plates of various kinds (e. g., platinum foil, spongy platinum, thin sheet gold, &c.) when opposed to the same oxidisable metal, such as copper or zinc, in contact with the same electrolytic fluid, e. g., dilute sulphuric acid or caustic soda solution.

VI. On the development of voltaic electricity by atmo­spheric oxidation

In a preliminary note on this subject (‘Roy. Soc. Proc.,’ vol. 42, p. 212), it has been shown that when copper is immersed in an aqueous solution of ammonia and opposed to an “ aëration plate ” of some conducting material not otherwise acted upon, lying horizontally on the surface of the fluid, a current flows continuously through a wire, &c., made to connect the two plates, the energy manifested by which is due to the absorption of atmospheric oxygen by the aëration plate and the indirect combination of this with the copper forming cuprous oxide which dissolves in the ammonia.