THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. I. — The Heating Effects produced oy Rontgen Rays in 

 Different Metals, and their Relation to the Question of 

 Changes in the Atom ; by H. A. Bumstead. 



The study of the phenomena of radio-activity during the past 

 five or six years, and, in particular, the brilliant series of 

 experiments and deductions which we owe to Rutherford, 

 have left little room for doubt that a certain proportion of the 

 atoms of radio-active elements are continually breaking up, 

 and that the constant emission of energy by these bodies is a 

 result of this atomic disintegration. This process in any 

 given radio-active body appears to be going on at a fixed and 

 definite rate which is characteristic of the particular substance 

 studied and which is quite uninfluenced by any external cir- 

 cumstances whatever. Although radio-active substances have 

 been subjected to the greatest extremes of temperature avail- 

 able in the laboratory, and to great variations in other physical 

 and chemical conditions, no certain results have been obtained 

 (so far as the writer is aware) which point to any correspond- 

 ing change in the rate of decay of the substance. In fact 

 the process of atomic disintegration has appeared to be quite 

 beyond human control.* 



On the other hand, all substances when illuminated with Ront- 

 gen rays, or with Becquerel rays of the 7-type, give out a com- 

 plex secondary radiation, part of which at least is wholly dif- 

 ferent in character from the primary radiation. For example, 

 the secondary radiation due to Rontgen rays consists in part 

 of negatively charged corpuscles or electrons which are not 

 present in primary rays. This suggests that there may be some 



* The apparent change (due to high temperature) in the rate of decay of 

 radium-excited activity, discovered by Curie and Danne, has been shown to 

 be due to the fact that the successive products of radium volatilized at dif- 

 ferent temperatures. Cf. Bionson, this Journal, July 1905. 



Am. Jour. Sci. — Fourth Series, Vol. XXI, No. 121. — January, 1906. 

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