45- RADiOACTlVK MINERALS IN SOUTH AFRICA. 



The radio-active effect on the piiotographic plate was faint, 

 even after an exposure of lo days, as shown m liate 13. (/. 



Carnotite with Uranium Ochre. 



During 1913 and 1914 a very large number of specimens 

 of tantalates and columbates from Little .\amaqualand, the 

 north-western corner of the Colony, were examined and analysed 

 with a view to ascertaining the proportion of tantalic and niobic 

 pentoxide in these minerals. In the course of these investiga- 

 tions a tine specimen of tantalite was observed to contain a 

 yellow earthy substance embedded in a cavity, and on being 

 exposed to the photograpliic plate, this substance exerted a 

 very distinct action after seven da} s (see Plate 14. a). On 

 analysing the yellow substance, it was found to contain 62.3 

 per cent, of uranic trioxide, and also a very small amount of 

 vanadic pentoxide. The yellow earthy substance may therefore 

 be considered a mixture of uranium ochre and carnotite, which 

 consists principally of vanadate of uranic oxide. 



Pitchblende. 



If we extend the boundary line of South Africa a little to the 

 north, say to the ec|uator, it will include (German I£ast Africa, 

 where pitchblende has been found in considerable quantity. The 

 author received a sample of this pitchblende in 1906 from Pro- 

 fessor Dr. Scheibe, of the Mining Academy, Berlin. Two 

 analyses have been made of a portion of this specimen, the 

 results of which indicated 79.52 per cent, and 79.38 per cent. 

 of uranic trioxide. It is very strongly radio-active : the 

 impression on the photographic plate after an exposure of seven 

 days is shown in Plate 14. h. 



Up to the present I have not heard of the occurrence of 

 pitchblende, the source of radium, in any other locality of South 

 Africa. Considering the fact that uranium ochre and carnotite 

 have been found in Little Namaciualand. it is not iiuprobable 

 that further prospecting operations will result in finding the 

 much-sought-after pitchblende in that most desolate part of 

 South Africa. 



Comet 1916b. — In April last Prof. Wolff, of Heidelberg, 

 announced the discovery, by means of photography, of a new 

 minor planet. It was, however, noted tha-t the supposed planet 

 possessed a stellar nucleus and a nebulous envelope. This enve- 

 lope subsequently developed into a small tail, and the object was 

 discovered to be a comet. The elements of its orbit were recently 

 computed by Berberich, and according to these it will not reach 

 perihelion until the middle of June, 191 7, fifteen months after 

 discovery. When discovered it must have been in the vicinity 

 of Jupiter's orbit, probably a record distance for discovery. If 

 it should prove to be a comet of exceptional size, it may become a 

 brilliant object towards the middle of 1917. 



