HYPOTHESIS OF RADIANT MATTER 57 



have a speed one tenth of the velocity of light, and a molecular mass 

 of atomic magnitude. They penetrate a few centimeters into air, pass 

 through thin aluminum foil but are stopped by denser metals. As they 

 are but slightly deviable in a magnetic field, their momentum is calcu- 

 lated to be enormous : until, however, better evidence of the total positive 

 charge which they carry has been obtained, we can not consider the 

 magnitude of the momentum as definitely established; especially since 

 their speed does not appear to be uniform. From experiments wherein 

 a particles are allowed to escape freely, and again restrained by a lead 

 cylinder surrounding radium, much of the apparent heat of the latter 

 body appears to be due to the impinging of the a rays upon the sur- 

 rounding surfaces. 



/?-Bays are similar to cathode rays ; they are less absorbable than the 

 a variety, and proceed at various speed, many approaching the velocity 

 of light; they are stopped by solids in proportion to their density. 



y-Eays are similar to X-rays, of great penetrating power, and they 

 are thought by some to be secondary effects of a and (3 rays, just as the 

 X-rays originate from the impact of cathode rays on the glass wall of 

 the Crookes tube. Besides, we have a multitude of conflicting accounts 

 of secondary tertiary rays, resulting from these three varieties. 



The chief method of research is the study of ionization, with the 

 interposition of screens and magnetic fields, to separate the different 

 kinds of rays. On the other hand, the varieties of rays emitted, their 

 relative strength, and their variations of intensity, are the character- 

 istics upon which the identification of the various so-called transforma- 

 tion-products of radio-active material is based. I have, therefore, 

 copied from Professor Butherford's book 2 tabulations of these properties. 



With regard to these various transformations, we should realize that 

 the majority of the names are titles of hypothetical substance, whose 

 existence within certain mixtures is assumed upon the evidence of their 

 momentary radio-activity. The only one really isolated is that emana- 

 tion which has all the properties of a gas, including that of condensi- 

 bility at low temperatures — with the exception that its liquid form 

 shows no vapor pressure — but has in addition remarkable energy effects, 

 and has, undoubtedly, undergone transformation in Eamsay's hands. 

 Bearing in mind the infinitesimal quantities of emanation which Earn- 

 say and his associates could obtain, we are alike astounded by their 

 marvelous manipulative dexterity and by the nature of their observa- 

 tions. First we had the gradual appearance of helium, when the ema- 

 nation was stored by itself; then came the appearance of neon, when 

 the emanation came into contact with water, the latter being partially 

 decomposed into oxygen and hydrogen; lastly the partial reduction of 

 copper nitrate solution, with the simultaneous appearance of lithium, 



2 " Radio-activity," 1905. 



