203 



dry. Oil heating over a spirit-lamp the colour changes 

 abruptly to pink, the change taking place below a red heat. 

 The composition of this sulphate is a matter of great interest, 

 as it obviously does not contain a great deal of barium. The 

 amount available for experiment, so far, has been too small 

 to admit of much detailed work being done on it, but a few 

 experiments of a qualitative character have tjeen made. 

 Neither the weight nor the activity of this sulphate is much 

 altered on treating it with a hot concentrated solution of 

 caustic soda, but the washed product from this treatment is 

 soluble in hydrochloric acid, giving a bright yellow solution. 

 Part of this colour is due to iron, as a small amount of this 

 is precipitated on the addition of ammonia. The addition 

 of ammonium oxalate to the acid solution also results in a 

 small amount of precipitate coming down after long standing. 

 However, until enough of this sulphate has been collected to 

 allow of quantitive work being done, it is impossible to say 

 definitely how the activity will distribute itself, though I 

 have good reason to believe that a product considerably more 

 active than I have isolated so far can be got without much 

 difficulty. 



In reviewing the results of this preliminary work two 

 points call for special comment. The first of these is the 

 invariable occurrence of carbon in the active ores. So far, 

 every specimen showing any marked activity has been found 

 to contain it, usually to the extent of several per cent. 

 Enough work has not yet been done to settle the question 

 definitely as to whether the carbon is present in the active 

 ores only, or whether it is also distributed through the in- 

 active material in the neighbourhood of the active deposit. 

 The distribution of the activity in the ore is very sharply 

 defined in some cases. A small hand specimen may show 

 very marked activity on one side, and be almost inactive on 

 the other. The carbon contents do not appear to bear any 

 quantitive relation to the activity. Some of the most active 

 specimens contain very little carbon, and, on the other hand, 

 some of the carbonaceous ore from Taylor's Shaft is only 

 slightly active. Mr. Rogers has suggested, in view of these 

 results, that, if it has not been done already, it might be well 

 to try the Mansfield copper deposits for activity, as these also 

 contain carbon. 



Burton's observation, that the petroleum from a deep 

 well in Ontario not only contained a large amount of radium 

 emanation, but left a solid deposit on evaporation, which 

 possessed permanent activity, is also of interest in this con- 

 nection. 



The second feature to which attention may be drawn 

 in the case of the Moonta ores is the facilitv with which the 



