﻿■±10 Sir W. Ramsay and Dr. Spencer on Chemical and 



potential series. This also disproves any suggestion that the 

 discharges are brought about by oxidation of the surface of 

 the plate, for it is inconceivable that palladium and hydrogen 

 should oxidize at the same rate. Measurements made with 

 various specimens of iron show that the carbon contained has 

 a retarding action, for the more carbon the iron contains the 

 less rapid is the rate of discharge. It will be notice 1 that, 

 with the exception of the first few elements, the rate of dis- 

 charge in Series A is much higher than that of Series B. It 

 is very possible that even in the first few elements this is also 

 the case, for the intervals of time were so short that an 

 increase of one-fifth of a second would reverse the position. 

 The reason for the difference in the rate of discharge may 

 possibly be explained by the hypothesis, as stated in the in- 

 troduction, that a metallic element is a compound of an ion 

 with one or more electrons. The action which takes place 

 under the influence of ultraviolet light might be conventionally 

 depicted by the equation 



Element = ion ~t n. Electrons. 



This action will proceed at a perfectly definite rate if all 

 other conditions remain constant. Suppose that such an 

 element is charged to a given potential, or, in other words, a 

 greater number of electrons distributed on its surface. Now 

 an element in its normal condition is able to retain a certain 

 number of electrons, but if a great many more are added it 

 will naturally hold them with very little force ; and, conse- 

 quently, when a detonator in the shape of ultraviolet light 

 is applied, they will be given off at a much greater rate than 

 when the plate is uncharged. An explanation for the 

 charging of the electroscope when sulphur and selenium 

 were measured, is probably to be found in the ease with 

 which these elements take up a charge themselves ; this is 

 rendered more probable by the fact that in several experi- 

 ments the sulphur was proved to be charged. Hallwachs 

 and Le Bon proved that an insulated plate takes up a positive 

 charge when placed in ultraviolet light. We repeated this ex- 

 periment, using a piece of magnesium attached to a positively 

 charged electroscope, and found that the rate of the natural 

 leak of the electroscope was retarded. The surfaces of all 

 the elements measured tire with extreme rapidity, so much 

 so in some cases that the first and most rapid discharge could 

 only be recovered after the plate had remained for several 

 days in the dark and had then again been polished. The 

 tiring of the plates and a possible explanation thereof will be 

 referred to later. 



