PROBLEMS OF INORGANIC CHEMISTRY. 41 



changes must belong to the domain of inorganic chemistry. It is true 

 that the methods of investigation are borrowed from the physical chem- 

 ist ; but the products lie in the province of the inorganic chemist. In- 

 deed, the different departments of chemistry are so interlaced that it 

 is impossible to pursue investigations in any one branch without bor- 

 rowing methods from the others; and the inorganic chemist must be 

 familiar with all chemistry, if he is to make notable progress in his 

 own branch of the subject. And if the substances and processes investi- 

 gated by the inorganic chemist are destined to become commercially 

 important, it is impossible to place the manufacture on a sound com- 

 mercial basis without ample knowledge of physical methods, and their 

 application to the most economical methods of accelerating certain 

 reactions and retarding others, so as to obtain the largest yield of the 

 required product at the smallest cost of time, labor and money. 



I have endeavored to sketch some of the aspects of inorganic chem- 

 istry with a view to suggesting problems for solution, or at least the 

 directions in which such problems are to be sought. But the develop- 

 ments of recent years have been so astonishing and so unexpected, that 

 I should fail in my duty were I not to allude to the phenomena of radio- 

 activity, and their bearing on the subject of my address. It is difficult 

 to gauge the relative importance of investigations in this field; but I 

 may be pardoned if I give a short account of what has already been 

 done, and point out lines of investigation which appear to me likely to 

 yield useful results. 



The wonderful discovery of radium by Madame Curie, the prepara- 

 tion of practically pure compounds of it, and the determination of its 

 atomic weight are familiar to all of you. Her discovery of polonium, 

 and Debierne's of actinium have also attracted much attention. The 

 recognition of the radioactivity of uranium by Becquerel, which gave 

 the first impulse to these discoveries, and of that of thorium by Schmidt, 

 is also well known. 



These substances, however, presented at first more interest for the 

 physicist than the chemist, on account of the extraordinary power which 

 they all possess of emitting ' rays.' At first, these rays were supposed 

 to constitute ethereal vibrations; but all the phenomena were not ex- 

 plicable on that supposition. Schmidt first, and Butherford and 

 Soddy later, found that certain so-called ' rays ' really consist of 

 gases; and that while thorium emits one kind, radium emits another; 

 and no doubt Debierne's actinium emits a third. The name ' emana- 

 tions ' was applied by Butherford to such radioactive bodies; he and 

 Soddy found that those of radium and thorium could be condensed 

 and frozen by exposure to the temperature of liquid air, and that they 

 were not destroyed or altered in any way by treatment with agents 

 which are able to separate all known gases from those of the argon 

 group, namely, red-hot magnesium-lime, and it was later found that 

 sparking with oxygen in presence of caustic potash did not affect the 



