August 21, 1914] 



SCIENCE 



265 



TEE CONSTITUTION OF ATOMS 

 The Physical Society of London visited 

 Cambridge, and at a meeting in tlie Cavendish 

 Laboratory, June 20, Sir J. J. Thomson, the 

 president, gave information of the results of 

 some important experiments he has been ma- 

 king -with regard to the production of very 

 soft Eontgen radiation by the impact of posi- 

 tive and slow cathode rays. According to the 

 report in the London Times Professor Thom- 

 son said he proposed to give them an account 

 of some recent experiments whose object it was 

 to fill up a gap in the kind of radiation that 

 they had at their disposal upon investigation 

 of the properties of the atom. The study of 

 Eontgen radiation had enabled them to prove 

 the existence of two separate rings of electrons, 

 one inside the other; the one was responsible 

 for what is known as the K kind of radiation, 

 and the other had the L characteristic, but the 

 L characteristic was so much softer than the 

 K that if they were to consider what would be 

 likely to be the properties of the radiation 

 given out by a third ring, if the rate of in- 

 crease in softness was anything like the same 

 proportion the radiation from the third ring 

 would come well within that region of radia- 

 tion which at present had not been studied, 

 and if they command a continuous series of 

 radiations, extending from the visible light 

 which affected the outer ring of electrons right 

 up to the hardest region of radiation, they 

 would be able to see how many separate vi- 

 brating systems, how many rings of electrons 

 there were inside the other, and, more than 

 that, they would be able, by the study of that 

 radiation, to gauge the number of electrons in 

 each ring, so that this study promised to give 

 them the means of determining the distribu- 

 tion of electrons throughout the atom. Li the 

 experiments two methods had been employed. 

 The first was the production of Eontgen radia- 

 tion by the impact of positively charged atoms. 

 By availing himself of the very remarkable 

 sensitiveness of the Schuman photographic 

 plate they had been enabled to get unmistak- 

 able evidence that as the positive rays im- 

 pinged against a surface they gave out a type 

 of Eontgen radiation. Professor Thomson de- 



scribed at length the apparatus he employed, 

 which in this case was a Crookes tube, and the 

 experiments he made. His second method was 

 by the impact of cathode rays, and they ar- 

 ranged the experiment so that they had the 

 speed of the cathode rays very much under 

 control. In this experiment an ordinary 

 Eontgen ray tube was employed. The photo- 

 graphic method. Professor Thomson continued, 

 was rather time wasting, and they had lately 

 tried experimenting with a substitute for the 

 photographic plate, and if they succeeded with 

 those experiments they probably would be able 

 to get on much more quickly. But even with 

 the photographic plate they hoped to make a 

 series of experiments which would enable them 

 to find how many rings of electrons there were 

 in an atom. 



HENBT EEMPBILL 



We have just received notice of the death, 

 July 25, at Oakland, Cal., of Henry Hemphill, 

 in his eighty-fifth year. 



Mr. Hemphill was born in Wilmington, 

 Del., in 1830, but for many years had been a 

 resident of the state of California. He was a 

 mason by trade and took great pride in his 

 proficiency. More than fifty years ago he be- 

 came interested in the shells of the Pacific 

 coast and formed one of a group of enthusi- 

 astic collectors which included Kellogg the 

 botanist, Harford, Voy, Stearns and others, of 

 which he was the last survivor. His trade 

 brought him in, at California union wages, 

 such a good income that he could not only 

 lay away a fair nest egg for his old age, but 

 take long vacations. During these periods he 

 visited Florida and all parts of the Pacific 

 coast south of British Columbia, and be- 

 came one of our most expert collectors of mol- 

 lusks. The genus of slugs, HempMllia, was 

 named in his honor by the late W. G. Binney, 

 and a host of species commemorate in like 

 manner his success as a collector. 



He published but few papers himself, but 

 was the cause indirectly of much publication 

 by others. He had a keen eye for relation- 

 ships and differences, and at times mounted 

 on large tablets series of land shells with radi- 



