Chemistry and Physics. 327 



his purpose to publish a detailed account of the investigation in 

 the Proceedings of the American Academy and perhaps elsewhere. 



J. T. 



8. Heating effect of the Radium Emanation. — It has been 

 shown that the radiation emitted from a radium compound in a 

 state of radio-active equilibrium may be divided into three parts : 



(1) A non separable radiation consisting entirely of a rays ; and 

 constituting about 25 per cent of the total radiation. 



(2) The radiation from the emanation occluded in the radium, 

 also consisting entirely of a rays. 



(3) The excited radiation produced in the mass of the radium, 

 consisting ot a, /?, and y rays. 



(2) and (3) together constitute about 75 per cent of the total 

 radiation. 



It is found that the emanation supplies 18 per cent, the non- 

 separable activity 25 per cent, and the excited activity 57 per 

 cent of the total activity of radium. On heating or dissolving a 

 radium compound in an open vessel, the emanation is released and 

 can be entirely removed by a current of air. The excited activ- 

 ity, or emanation X, is non-volatile, and being left in the radium 

 immediately begins to decay. Since fresh emanation is being 

 constantly produced by the radium and occluded- in it, the activ- 

 ity of the radium after falling to a minimum gradually rises again, 

 and in the course of a month nearly reaches its original constant 

 value. Interesting curves are given of the energy of the various 

 forms of activity ; and calculations of the amount of heat from 

 the emanation. It is computed that the amount of heat liberated 

 per hour from l cc of the emanation lies between 1-25X10 5 and 

 1*25 X 10 6 gram-calories. This amount of heat would probably be 

 sufficient to raise to a red heat, if not to melt down, the glass tube 

 containing it. One pound weight of the emanation w T ould initi- 

 ally radiate energy at the rate of 10 4 to 1 5 horse-power, and while 

 the heating continued would emit an amount of energy between 

 6X10 4 and 6X10 5 hori»e power days. According to the author's 

 disintegration hypothesis, this energy is derived from the energy 

 latent in the radium atoms and is released in the various stages of 

 their disintegration. — Rutherford and Barnes in Phil. Mag., 

 Feb., 1904, pp. 202-219, j. t. 



9. Nature of the Emanations from Radium. — Lord Kelvin 

 finds it difficult to believe in the atomic disintegration hypothesis 

 of Rutherford, and suggests that radium may transform etheric 

 vibrations into its peculiar manifestations of energy, just as a 

 black cloth in a test tube filled with water shows an increase of 

 heat over a similar receptacle filled with water and containing a 

 piece of white cloth.— Phil. Mag., Feb., 1904, pp. 220-222. 



J. T. 



