neio thorium and uranium Mineral. 10 L 



much purer than the first lot. There is at most an indication 

 that FeO, CaO, alkalies, P 2 5 and perhaps some water arise from 

 imparities. Titanium, manganese, and fluorine are not present in 

 the mineral. 



a b Thoro-gummite (H. & M.) 



SiOo 13-90 13-92 SiO a 13085 



U0 2 ._ 22-40 21-86f TJO3 22-43 



ZrOo? -88 "I Th0 2 41-44 



ThO. I 4 - 30 * I A1 2 3 -965 



CeoOs? i J- lost Fe 2 3 -845 



Lao0 8 ) . oa (Ce.Y). 2 3 etc. 6*69 (At. W. 135) 



Y. 2 b 3 } gr0UpS — 1-86 J PbO__ 2-16 



PbO 3-T4 3-92 CaO -41 



FeO 115 % p i°5 1-19 



CaO.. -59 -44 H 2 T-88 



MgO -10 -13 Moisture 123 



KoO -42 



(Na,Li) 2 -68 j" <0 98-325 



P0O5 -67 -46 



H 2 above 100° C. 4-31 



H 2 below 100° C. '50 -35 



96-50 



Taken by themselves these results are incapable of translation 

 through the medium of molecular weights into any precise 

 formula, but they become of interest when compared with the 

 accompanying analysis of thoro-gummite by Hidden and Mackin- 

 tosh. § It is then seen that the opinion of Mr. Hidden regarding 

 the derivation of thoro-gummite from the present mineral was 

 fully justified. It is in fact remarkable, considering the great 

 molecular alteration that must have taken place, as determined 

 by the totally different appearance of the two minerals, that so 

 little loss of substance has taken place. Almost the sole change 

 has consisted in an oxidation of uranous oxide and an increase in 

 the hydration. These facts render not altogether safe the assump- 

 tion above made that all uranium and iron in the new mineral 

 exist there in the lower forms of oxidation, and they furthermore 

 indicate that the black mineral itself may have already under- 

 gone oxidation and hydration without this being manifest to the 

 eye — a supposition which is strengthened by the loss at 100° C. 

 of half a per cent of water, and in fact by the intimate union 

 which existed between the two minerals when received. Such 

 material alteration without corresponding physical evidence of it, 

 seems to be common among uraninites. The original condition 

 of the mineral may then have been one in which uranium and 

 iron were entirely in the lower state of oxidation and in which 



- The precipitate by potassium hydroxide was pure white after long action of 

 chlorine. It may, however, have contained a trace of cerium. 



f Would be slightly increased by uranium which was not separated from the 

 earths. 



X The estimation of iron miscarried, but the amount was unquestionably less 

 than in a. 



§This Journal, xxxviii, 480, 1889. 



