June 19, 1903.] 



SCIENCE. 



991 



sity, Montreal, read a paper on ' Eadio-active 

 Processes.' According to tlie report in the 

 London Times he pointed out that the radio- 

 active bodies uranium, thorium and radium 

 were continuously and apparently spontane- 

 ously giving off three distinct types of radia- 

 tion. There were, first, the a rays, which 

 were projected bodies, flights of positively 

 charged material particles, which were prom- 

 inent in causing conductivity in gases, were 

 easily absorbed, moved with great velocity, 

 and carried a large amount of energy. Sec- 

 ondly, there were the /? rays, which were ap- 

 parently the same as the cathode rays of ordi- 

 nary vactium tubes, though they traveled 

 faster, and hence had very considerable 

 penetrating powers. They were negatively 

 charged. Thirdly, there were the y rays, 

 which appeared very similar to ordinary 

 X-rays. In addition some of the substances 

 gave off something else. Thorium oxide, for 

 example, emitted an emanation which appeared 

 to be matter in gaseous state, and could be 

 carried along by air-streams, and radium gave 

 a similar emanation, which differed from that 

 of thorium in that its effects were far more 

 persistent. These emanations behaved like 

 radio-active gases; their diffusion could be 

 measured, and they could be occluded in radio- 

 active bodies, while the fact that they could 

 be condensed by the cold of liquid air rend- 

 ered them difficult of explanation except on 

 the assumption that they consisted of ma- 

 terial bodies. These emanations induced or 

 excited radio-activity in every body in their 

 neighborhood, and this excited activity, like 

 that of the emanations, decayed at a constant 

 rate. Apparently the emanations themselves 

 could not be affected by any chemical treat- 

 ment, but behaved like inert gases, wherein 

 they differed from the excited activity which 

 chemical treatment did affect. It had been 

 found possible to separate from radio-active 

 bodies a radio-active constituent; thus by a 

 chemical method Crookes had removed all ac- 

 tivity from uranium, and the lecturer and 

 Mr. Soddy had found that the radio-active 

 constituent, which might be called thorium 

 X, could be separated from thorium. In 



time, however, the former lost its activity 

 and the latter regained it. It seemed as if 

 radio-active bodies were continually under- 

 going some change by which new substances 

 were being produced ; thus thorium from which 

 all the thorium X had been removed would 

 in a few weeks yield as much as before. The 

 radiations had a close connection with chem- 

 ical changes. It might be supposed that the 

 atoms of the radio-active bodies were in a 

 state of unstable equilibrium, and sent off 

 positively charged bodies. But the thorium 

 atom which had sent off such a positive body 

 was chemically altered, and thorium X was 

 equivalent to thorium minus the expelled body. 

 The thorium X atom was also unstable, and in 

 turn threw off another positive body, and so 

 the process went on, the changes that occurred 

 being measured by the activity of the preced- 

 ing stage. The main radio-active processes 

 threw off positive bodies, which were thus the 

 most important, and negative electrons and 

 cathode rays only appeared in the last stages. 

 It was to expected that only a small number 

 of a rays would be thrown off; these were 

 quickly absorbed, and thus the radium was 

 subject to bombardment by itself, with the 

 result that it grew hot and maintained its tem- 

 perature above that of its surroundings, as 

 observed by Curie. The amount of energy 

 given out was enormous ; it might be calculated 

 that a gram of radium during its life 

 would give out enough to raise 500 tons a 

 mile high. But there was no reason why such 

 huge stores of energy should be thought to 

 exist only in radio-active bodies; they might 

 exist in every atom, although we had not yet 

 happened to obtain any knowledge of their 

 existence. 



UNIVERSITY AND EDUCATIONAL NEWS. 

 President Butlek announced at the com- 

 mencement exercises of Columbia University 

 that the trustees had decided to purchase the 

 two blocks of land south of the present site 

 of the university at a cost of $2,000,000. He 

 also announced a gift of $300,000 from Mrs. 

 Helen Hartley Jenkins and Mr. Marcellus 

 Hartley Dodge, a member of the senior class. 



