system, so also will a similar direction be given to the effects of external motion. Every motion tending to propel forward the blood,
will hence assist the powers of the heart; but such as have a contrary tendency will be resisted by the interposition of the valves, and
cannot occasion proportional obstruction to the regular progress of
the blood; the heart is thus assisted in the work of restoring a system, which has recently struggled with some violent attack, or allowed, as it were, to rest from a labour to which it is no longer equal,
when the powers of life are nearly exhausted by some lingering disorder.
It is conceived that all the other animal functions must participate in the relief thus afi'orded to so important an organ; and it is remarked, that even the powers of the mind itself, though most remote from our conception of material agents, are, in many persons, thus immediately affected, by the consequences of a merely mechanical operation.
Mr. Davy having from the commencement of his electro-chemical researches, communicated the several steps of his progress to the Society, takes the present opportunity of reporting the results of his further inquiries under four principal heads. First, on the nature of the metals of the fixed alkalies. Second, on the nature of hydrogen and composition of ammonia. Thirdly, on the metals of the earths; and, Fourthly, he makes a comparison between the antiphlogistic doctrine, and a modified phlogistic hypothesis.
When Mr. Davy first communicated to us his discoveries of potassium and sodium, he adopted, as most probable, the antiphlogistic interpretation of the phenomena, and considered potassium and sodium as simple metallic bodies, of which potash and soda are the oxides. The same experiments have since been repeated by others with the same results, but the explanations given by different chemists have been various. The theory which has appeared most deserving the author’s notice, and is more particularly controverted, is that of Messrs. Gay-Lussac and Thenard, who conceive these metals to be compounds of their respective alkalies with hydrogen; although in the interpretation of their own production of a metallic substance from boracic acid, they relapse again into the antiphlogistic doctrine, and suppose themselves to have eil'ected a decomposition, by abstraction of oxygen from it.
Since the principal experiment on which Messrs. Gay-Lussac and Thenard rely, is that in which ammonia is acted upon by potash, Mr. Davy details a great number of modes in which he has varied the experiment with the utmost care to avoid moisture, which appears to
