258 B. B. Boltwood — Ultimate Disintegration 



actually a disintegration product, is certainly slow, for only 

 very small relative amounts of it are found in some compara- 

 tively old minerals. In primary minerals the amount of lead 

 present is always greatly in excess of the barium, which occurs 

 only in traces made evident in the separation of the radium 

 from considerable quantities of material. As in the case of 

 bismuth, the barium might be produced either from a slowly 

 disintegrating parent or from a radio-active body existing only 

 in comparatively small amounts in the radio-active system. 

 Certain data, to be published later by the writer, have been 

 obtained which seem to indicate that the amount of actinium 

 in a radio-active mineral is dependent on the amount of ura- 

 nium present, thus suggesting that uranium is the parent of 

 actinium as well as of radium, but other results lead to the 

 conclusion* that actinium is not a direct result in the same 

 sense as is radium. The quantity of actinium produced in a 

 radio-active mineral is apparently small as compared to the 

 radium, and it may therefore be possible that the barium pres- 

 ent is a final product of the actinium. 



Hydrogen. 

 A point which has caused much speculation on the part of 

 mineralogists is the apparent hydration of the greater number, 

 if not all, of those minerals which are now known to contain 

 radio-active constituents. That this state of affairs is in some 

 way connected with the disintegration processes taking place 

 in these compounds would not appear impossible, since the 

 production of such an elementary substance as hydrogen as one 

 of the j:>roducts of the radio-active decay of the atoms of 

 elements of high atomic weight is in fact suggested by much 

 of the data on the nature of the expelled alpha particles. f It 

 would seem possible that the difference in ionizing power, of 

 the power of penetration, etc., shown by the alpha particles 

 from certain of the radio-active types of material may perhaps 

 be due to a difference in the mass of the projected particle, 

 and that the occurrence of notable quantities of water in the 

 primary radio-active minerals, which is otherwise most difficult 

 to explain, may be considered as indicating that hydrogen is in 

 fact one of the disintegration products, originating as an alpha- 

 ray particle from one or more of the numerous radio-active 

 substances which have already been identified. The origina- 

 tion of hydrogen in a mineral containing oxidized constituents 

 would in all probability lead to the reduction of the more 

 readily reducible of these with the consequent production of 

 Avater. 



* Eutherford and Boltwood, this Journal, xx, 56 (1905). 

 f Eutherford, " Eadio-activity," p. 328 and elsewhere. 



