Page:Proceedings of the Royal Society of London Vol 1.djvu/270

Rh potash or soda was to increase the time necessary for this transfer. Muriatic or nitric acids were also transmitted through alkaline solu- tions; and, vice versd, alkaline matter, by changing the arrangement of the liquids, was transmissible through the acids: even magnesia was transferred like the other bases. But when it was attempted to pass sulphuric acid through aqueous solutions of barytes or of stron- tian, on the contrary, the sulphate of those earths was deposited in the intermediate tube.

Muriate of barytes being positive, sulphate of potash intermediate, and water negative, potash appeared in the water, and sulphate of barytes was deposited in the intermediate vessel.

Muriate of barytes being negative, sulphate of silver intermediate, and water positive, sulphuric acid only appeared in the water, and muriate of silver was deposited in the intermediate vessel.

Mr. Davy then proceeds to develop the theory of these phenoa mena: and he ﬁrst considers the mode of decomposition and transi- tion. Hydrogen, alkaline substances, and metallic oxides, are at- tracted by negatively electriﬁed metallic substances, and repelled by positive ones: contrary eﬂ’ects take place with oxygen and the acids. He thinks these electric energies are communicated from one particle to another of the same kind, so as to establish a conducting chain in the ﬂuid, as acid matter is always found in the alkaline solutions through which it is transferred, as long as any acid matter remains at the original source. It is possible that there may be, in some cases, a succession of decompositions and recompositions; but the process is not absolutely necessary, as pure acids and alkalies pass thmngh water to the points by which they are attracted. It appears that this power of transference is overcome by gravity in attempting to pass barytes through sulphuric acid, or muriatic acid through sul- phate of silver. To these instances he adds, that magnesia and the metallic oxides will not pass through an intermediate vessel of water, but sink to the bottom.

In the decomposition of water, a particle of oxygen is attracted by the positive point, and at the same time a particle of hydrogen is re- pelled by it; the opposite process takes place at the negative point: and in the middle of the circuit there must be a new combination of the repelled matter, in the same manner as when two portions of muriate of soda are separated by water; muriatic is repelled from the negative side, and soda from the positive side; so that muriate of soda is composed in the middle vessel.

Although similar effects could not be produced by silently passing

a strong current of electricity from an electrical machine for four hours, through sulphate of potash, yet they were produced by using platina Wires 71.,th of an inch in diameter, cemented in glass tubes; so that no doubt can arise but that the principle of action is the same in common as in voltaic electricity.

It was known that many bodies brought into contact and then separated, exhibited opposite states of electricity; and Mr. Davy himself had observed, that when acid and alkaline solutions were em-