264 B. B. Boltwood — Ultimate Disintegration 



Table II. 



Primary Minerals. 



Species. Locality. Th0 2 U0 2 PbO H 2 He Eeference. 



Thorite, Hittero, Norway 48-66 900 1 1*26 10-88 X a Dana,p.488 



Mackintoshite, Llano Co.", Tex. 45-30 22-40 3-74 4*31 X b A 1 



Yttrialite, Llano Co., Tex 10-85 1*64 0-80 0-32 X c a' 2 



Thorianite, Ceylon 78-86 2 2-59 X cl 0-39$ A 3 



Samarskite 3 10-13^ 3-1$ X e 



" (?) Colorado 3-64 4-02 0*72 1-58 ? Dana,p.740 



Annerodite, Annerod, Nor. _.. 2*37 16-28 2-40 8-19 .? Dana,p.741 



Euxenite _ 3 5-12$ 0*92 471 ? Dana, p. 744 



Hielmite, Falun, Sweden ? 2'34 4 0-21 2-23 X e Dana, p. 742 



Polycrase, Slattakra, Nor. 3*51 18-45 092 4*71 X e D*ana,p. 745 



Fergusonite, Llano Co., Tex... 0'83 7'05 5 L43 2*02 ? Dana,p.730 



" ._ ? 3-81 4 0-16 ? 0-03 A 4 



Xenotime, Naresto, Sweden. __ 2-43 3'48 4 0'68 1*77 X e Dana,p.749 



Monazite, North Carolina 5'00 0-40 6 tr. 0*20 X e 



Secondary Minerals. 

 U0 3 



Gummite, North Carolina 7 75-20 5'57 10*54 ? Dana,p.892 



Thorogummite, Llano Co., Tex. 41-44 22*43 2-16 7*88 ? A B 



Carnotite, Colorado 0*0 52-25 0-25 3*06 8 A 6 



IJranophane, North Carolina 9 66-67 0-60 12-02' ? Dana,p.699 



1 U 2 3 . 2 UO 2 6-03 4-UO 3 9-07. 



3 Hofmann and Strauss (Berichte, xxxiii, 3126) state that they found both 

 thorium and lead in samarskite and in euxenite. 



4 TJO3. 5 U0 3 and TJ0 2 . 



6 The composition of monazite given above is derived from experiments 

 of the writer. 



7 Specimens of gummite from North Carolina analyzed by the writer have 

 been found to contain from 2 to 3 per cent, of thoria. 



8 It is stated by Adams (this Journal, xix, 321 (1905) that helium is absent 

 from this mineral, which is to be expected since it is highly porous and of 

 recent formation. 



9 Samples of this material have been examined by the writer in which no 

 thorium could be detected. 



X a Helium has been found in the variety of thorite known as orangite. 



X b Hillebrand's experiments suggest the presence of helium in this mineral. 



X c Including this species among the primary minerals is possibly open to 

 objection. Hillebrand's exj^eriments would seem to indicate that it contains 

 from l cc to 2 CC of helium per gram. 



X d The analyses of Dunstan and Blake (see Ref.) do not indicate the 

 presence of water, but several tests made by the writer, on samples kindly 

 supplied by Mr. Geo. F. Kunz, suggest the presence of water in quite notable 

 quantities. 



X e The occurrence of helium in samarskite, hielmite, polycrase, xenotime, 

 monazite, orangite, and other radio-active minerals is described in papers 

 by Ramsay, Collie and Travers (Jour. Chem. Soc. Lond., lxvii, 684) and 

 Ramsay and Travers (Proc. Roy. Soc. Lond., lx, 442). 



Aj W. F. Hillebrand, this Journal, xlvi, 101 (1893). 



A 2 Hillebrand, this Journal, xiii, 195 (1902). 



A 3 Dunstan and Blake, Proc. Roy. Soc. Lond. (A), lxxvi, 253 (1905). 



A 4 Ramsay and Travers, Proc. Roy. Soc. Lond., lii, 316 (1898). 



A 5 Hillebrand and Mackintosh, this Journal, xxxviii, 480 (1889). 



A G Hillebrand and Ransom e, this Journal, x, 120 (1900). 



