§ 99_S_. Initial positive charges were not completely dissipated; negative charges were not only completely dissipated but the bodies acquired positive charges. Disks in the neutral state were charged positively by the X-rays the same as takes place with ultra-violet rays. The final positive potential was greater for copper than for zinc and still greater for retort carbon (“_le carbon de cornue_”) 90_c_. at end. The various results are not conflicting if the particular materials are taken into accounts. 90_c_ at end. 90_c_. The experiments of Prof. Minchin, an expert in such measurements, are properly described here, in that they seem to clear up the superficial ambiguity. He formulated the conclusion (_The Elect._, Lon., Mar. 27, ’96, p. 736) thus:—“The X-rays charge some bodies positively and some negatively, and whatever charge a body may receive by other means, the X-rays change it, both in magnitude and sign, to the charge which they independently give to the body.” Thus, in the case of magnesium, if the same is first positively charged by any suitable means, then will the X-rays not only discharge it, but electrify it negatively, while if this metal is first negatively charged, the X-rays either diminish or increase the discharge. It must be remembered, however, that this is not true with all metals, for he found that gold, silver, copper, platinum, iron, aluminum, bismuth, steel and antimony, are all positively electrified. 90_d_. BENOIST & HERMUZESCU’S EXPERIMENT. NEGATIVE CHARGES DISSIPATED FASTER THAN POSITIVE BY X-RAYS. RATE DEPENDS UPON ABSORPTION. LAW FORMULATED. _Comptes Rendus_, Feb. 3, Mar. 17 and April 27, ’96. They observed that the rays dissipated entirely the charge of electrified bodies in their path, and that negative charges were dissipated more rapidly than positive. § 99_Q_. They also noticed the discharge augments with the opaqueness of the body and that the effect is more considerable with two thin superposed sheets than with one. In experimenting upon the influence of the discharge of the gaseous dielectric in which the bodies were located, they formulated the following law. The rapidity of the dissipation of the electric charge of an electrified body under the same condition varies as the square root of the density of the gas surrounding the body. The dissipation of the electric charge depends upon the nature of the electrified body, due to a sort of absorbing power (§ 99_M_) connected with the opaqueness of the body and upon the nature of the surrounding gas, due to the density of the gas or when passing from one gas to another. (From trans. by Louis M. Pignolet.)