rRKSIDENTIAI, ADDRESS. 475 



Au interesting question awaiting solution is the probable constitution of this 

 core. 



The above is but an example of the many fascinating problems upon which 

 fresh light has been thrown by the revelations of recent discoveries in radio- 

 activity, and the temptation to dwell on such themes is correspondingly great ; 

 but I feel that such a tasl( should be committed to hands more capable than 

 mine. 



Fortunately, in tlie discussions which will talce place during our meeting 

 ample opportunity will be afforded those entitled to speak with authority. Never- 

 theless, there are one or two farther aspects of the matter which I will venture to 

 touch upon, although but an onlooker. I would, first of all, urge the importance of 

 a study of what may be termed the natural history of the elements. We require 

 more information as to their comparative proportions in different localities. The 

 fact that, given the amount of uranium in a sample of native rock, we can predict 

 with certainty the amount of radium contained in the same specimen is of 

 startling signiiicanco. 



The natural law which governs the proportions of these two substances may 

 have a far wider reaching scope than we at present suspect. Nature appears to 

 present to us a grouping which would not naturally have occurred to the mind of 

 the chemist: lead and silver, copper and gold, and, again, platinum and iridium, 

 seem invariably to be introduced to us by Nature as if bearing to each other some 

 kind of blood relationship. 



The facts we already possess seem dimly to indicate some close relation 

 between elements which we have hitherto considered as outside the bounds of 

 consanguinity, and for a fuller knowledge of this important branch of natural 

 history we require the assistance of the practical engineer, the geologist, the 

 metallurgist, and the chemist. 



Many of the results arrived at by the investigators into the phenomena of 

 radio-activity can apparently only be verified by the lapse of considerable intervals 

 of time. It is probable, for example, that we can estimate with some degree of 

 accuracy the time required for the dissolution of half a given mass of uranium or 

 radium, but the complete verification of our inferences must probably be left to a 

 future generation. If we accept this view, it is our duty to provide our successors 

 with data on which their conclusions may be based. If, for example, carefully 

 determined masses of the more radio-active substances could be placed in such 

 circumstances as to remain untouched until the meeting of this Association some 

 hundred years hence, our successors, who would doubtless be equipped with 

 apparatus of research more accurate and more sensitive than any in our pos- 

 session, would at all events be placed in a position to establish by direct methods 

 the accuracy of inferences based upon the experimental data now at our disposal. 

 This task is one which, it appears to me, might well be undertaken by Section A, 

 and I trust that this suggestion may be held worthy of some consideration. 



It appears probable that one gramme of radium diminishes in weight by about 

 half a milligramme per annum ; hence, if the funds of this Society admitted of the 

 imprisonment of some definite mass of radium, our successors a hundred years 

 hence would, even if they possessed only the apparatus now at our disposal, bo 

 able to determine its loss with sufficient accuracy to enable them to verify the 

 truth of the conclusions arrived at by the physicist of to-day, while the investiga. 

 tion of the radio-activity of the residue would possibly throw light on many 

 problems now awaiting solution. 



It would appear that if we made a similar imprisonment of uranium, a like 

 degree of accuracy would not be attainable until after the lapse of half a million 

 years, and I am afraid that our interest in the work of our successors cannot be 

 expected to cover so long a period. Nevertheless, it is probable that the presence 

 of the products of decomposition could easily be detected after the lapse of a 

 comparatively short interval of time. 



The experiment might well be extended so as to include examples of all the 

 elements capable of such treatment ; and with each prisoner should be placed a full 

 record of its phpical copstdnts, such ?s mass, densitjr, electricftl conductivity, 



