Products of the Radio-active Elements. 267 



tions of uranium and the rare earths. Others of the rare 

 earths present might be themselves concentrated to form such 

 minerals as allanite and gadolinite, confounds containing but 

 relatively small proportions of the radio-elements. 



When uraninite is found in metalliferous veins the general 

 indications point to its transportation hither from greater 

 depths by thermal waters and its deposition at a temperature 

 considerably lower than that existing in the plastic pegmatite. 

 The association of the secondary uraninites with the sulphides 

 of iron, copper, lead, bismuth and other metals is indicative of 

 conditions of deposit unfavorable to the simultaneous produc- 

 tion of rare earth minerals, which have never been observed to 

 occur under similar conditions in any locality. 



The mode of occurrence of radio-active minerals would 

 therefore appear to offer certain valuable data on the processes 

 taking place in the radio-elements and the products formed by 

 their disintegration. 



Origin of Elements. 

 If it can be ultimately demonstrated that lead, bismuth, 

 barium, hydrogen and argon, or any one of them, actually 

 result from the disintegration of uranium, an interesting ques- 

 tion which naturally arises will be : Have the quantities of 

 these chemical elements already existing been produced wholly 

 in the same manner? Any discussion of this problem at the 

 present time would certainly be premature, but the time may 

 not be very far remote when this question will deserve serious 

 consideration. 



Summary. 



Various data have been presented which are interpreted as 

 indicating that the ultimate disintegration products of the 

 radio-elements may include lead, bismuth, barium, the rare 

 earths, hydrogen and argon. 



The writer is fully conscious of the meagerness of the data 

 upon which the hypothesis of the production of these substances 

 is founded, but the suggestions are made in the hope that the 

 attention of other investigators may be directed to the possi- 

 bilities offered by a careful study of the composition and 

 occurrence of the radio-active minerals, and that their interest 

 may be sufficiently awakened to induce them to independently 

 undertake the experimental investigation of the theories which 

 have been suggested. 



139 Orange St., New Haven, Conn. 

 August 16, 1905. 



