I placed under a bell-glass, forming an insulated plenum, a pile consisting of fifty plates of silver and zinc. Next morning I observed that the water had risen some inches, indicating that a great absorption of air had taken place. Having then introduced a taper into the receiver, it was immediately extinguished. The pile, without being arranged anew, was placed under the same receiver; and on forming an insulated plenum, I observed, after twenty-four hours had elapsed, a sensible absorption of air. A taper was then introduced, and I obtained the same result. I replaced the pile under the receiver, and found, on the third and following days, that the pile retained its moisture, so that till the tenth day it gave analogous results. I repeated the same experiment with oxygen gas, and found, six days after, that the water in the bell had risen a foot. EXPERIMENT V. The same results may be obtained without employing large piles and large receivers. In general, it will be sufficient to arrange, in alternate strata, some plates of heterogeneous metals. If two plates of copper and zinc be placed under a bell an inch and a half in diameter, and three inches in height, and if an insulated plenum be then formed, two days after the water will have risen about half an inch. Having repeated the experiment with different metals, I found that a greater or less absorption of air had taken place, according to the difference of their nature and combination. This inspired me with the idea of making a series of experiments with different metals; and I hope to be able, at some future period, to form a table of the different heights of the fluid, which may serve to determine how far they are respectively susceptible of oxidation. However, to ascertain the oxidation of metals with precision, pieces of coin mixed with alloy ought not to be employed. Pure metals, formed into small piles, must be subjected to observation, and ought to be placed under equal bells, at the same temperature as that of the atmosphere. Until it be proved that the absorption of oxygen in the above experiments is merely a chemical effect, altogether unconnected with the action of Galvanism, I think I may be allowed to avail myself of it to prove the proposed analogy. EXPERIMENT VI.