Page:Proceedings of the Royal Society of London Vol 1.djvu/334

Rh wire by which the power was conveyed from the negative end of the battery. Lead, silver, copper, and iron, were successively employed; and it was by means of the last that the most distinct results were obtained.

When an iron wire, one seventieth of an inch in diameter, was made the conductor on the negative side, and brought into contact with moistened barytes or strontites, lime or magnesia, alumine or silex, the globule formed by fusion at the end of the wire appeared in each case to be alloyed with something capable of acting upon water; but those last named had, in succession, less action than the preceding.

The author had not himself used mercury as a means of obtaining the bases in a state of alloy till informed by a letter from Professor Berzelius of Stockholm, who has used it with success for the decomposition of lime and barytes. And Mr. Davy has found it to succeed equally with strontites and magnesia. And although mercury alone failed of effecting the decomposition of alumine and silex, yet when an alloy of mercury and potassium was made the medium of communication even with these bodies, they each appeared to be decom- posed by assistance of the afﬁnity of potassium for their bases.

The author also informs us of his success in repeating an experi- ment of Professor Benelius and Mr. Pontin, on the decomposition of ammonia: a globule of mercury being inserted in a small cavity made in a piece of carbonate or muriate of ammonia slightly moisten- ed, they are placed together on a plate of platina positively electri- ﬁed, and the wire from the negative end of the battery is applied to the mercury. The globule soon increases very considerably in bulk, and becomes converted into a soft amalgam, which absorbs oxygen from the atmosphere, or decomposes water into which it is thrown, and forms ammonia, While the globule gradually recovers its ﬂuidity, and is reduced to its original size before the experimth

Since the degree and manner in which the circulation of the blood depends upon the muscular and elastic powers of the heart and arteries are questions belonging to the most reﬁned departments of hydraulics, the author has already submitted to the Society those gene- ral principles upon which he designs, in the present lecture, let, to inquire what would be the nature of the circulation if the vessels were as inelastic as glass or bone; 2ndly, in what manner the pulse would be transmitted if the tubes were merely elastic; 3rdly, What actions may be ascribed to their muscular coats; and, lastly, what disturbances are occasioned in different kinds of fevers and inﬂammations.

In order to determine the velocity of the blood in different parts, it is necessary to estimate the pressure by which it is urged forward, and the resistance opposed to its motion. From the experiments of