PRESIDENT S ADDRESS. 



13 



Towards the end of last century the study of Inorganic 

 Chemistry and of Mineral Chemistry received a new impetus 

 through the discovery of radium by Madame Curie in Paris, 

 and of the radio-activity of thorium — a rare metal — and of 

 thorium compounds by Professor Schmidt of Erlangen. Since 

 the discovery of radium we have from time to time read of new- 

 discoveries in connection with radium and the constitution of 

 matter, of the atoms composing matter, of the transformation 

 of matter, of the wonderful physiological action of radium and 

 radium emanation. The latter subject is of great interest to the 

 general public. No doubt our medical men will have read with 

 the keenest interest in the British Medical Journal the articles 

 of Professor His of Berlin on the cures effected by the applica- 

 tion of radium emanation in cases of gout and rheumatism, and 

 of Dr. William Armstrong on Radium Water Therapy. This 

 subject, the study of Radium Water Therapy, is still in its 

 infancy, but will no doubt be followed u]) assiduously, and the 

 results hitherto obtained are surprising and marvellous. 



\ shall not detain you longer with the subject of Radium ; 

 suffice it to say that I have found the springs at Montagu and 

 Aliwal North distinctly radio-active, due to the presence of 

 emanation, and that this emanation is radium emanation and not 

 thorium emanation. The radium is associated in minerals princi- 

 pally with uranium. T have been searching now for four vears 

 for radium in South African minerals, but up to the present with 

 only negative results. But since pitchblende, the principal 

 source of radium, is found so far north as German East Africa. 

 and since some of our mineral waters contain radium emanation, 

 I cannot help thinking that radium-containing minerals do occur 

 also in South Africa, and will eventually be found. At all 

 events, T intend continuing the search for radium in South 

 Africa. 



In connection with the study of the radio-active minerals 

 and elements a very important discovery was recently made by 

 Professor Dr. Otto Hahn, of Berlin, of two radio-active sub- 

 stances, mesothorium and radiothorium. These two substances 

 are formed from thorium in a similar manner to that in which 

 radium is derived from uranium. Thorium oxide is largely 

 employed for making the mantles of incandescent lamps, and 

 is almost exclusively prepared from the monazite sands occurring 

 on the coast of Brazil. The bye-products in the manufacture 

 of thorium oxide mostly contain mesothorium and radiothorium. 

 and were used by Professor Otto Hahn for the preparation of 

 these two new elements, which emit the same rays as radium 

 and act in the same manner. The life of these two elements is, 

 however, not of the same duration as the life of radium, since 

 they break up after ten to twenty years into non-radio-active 

 substances, the nature of which is, however, at present little 

 known. Mesothorium and radiothorium can, however, be 



