358 



SCIENCE. 



[N. S. Vol. XXIV. No. 612. 



what may be termed the natural history of 

 the elements. We require more informa- 

 tion 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 significance. 



The natural law which governs the pro- 

 portions of these two substances may have 

 a far wider-reaching scope than we at pres- 

 ent 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 invari- 

 ably 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 radioactive substances could be 

 placed in such circumstances as to remain 

 untouched until the meeting of this asso- 

 ciation some hundred years hence, our suc- 



cessors, who would doubtless be equipped 

 with apparatus of research more accurate 

 and more sensitive than any in our posses- 

 sion, would at all events be placed in a 

 position to establish by direct methods the 

 accuracy of inferences based upon the ex- 

 perimental 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 gram of 

 radium diminishes in weight by about half 

 a milligram per annum ; hence, if the funds 

 of this society admitted of the imprison- 

 ment of some definite mass of radium, our 

 successors a hundred years hence would, 

 even if they possessed only the apparatus 

 now at our disposal, be 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 investigation of the radioactivity of 

 the residue would possibly throw light on 

 many problems now awaiting solution. 



It would appear that if we made a sim- 

 ilar imprisonment of uranium, a like de- 

 gree of accuracy would not be attainable 

 until after the lapse of half a million yeai*s, 

 and I am afraid that our interest in the 

 work of our successors can not be expected 

 to cover so long a period. Nevertheless, it 

 is probable that the presence of the prod- 

 ucts of decomposition could easily be de- 

 tected after the lapse of a comparatively 

 short interval of time. 



The experiment might well be extended 

 so as to include examples of all the ele- 

 ments capable of such treatment ; and with 

 each prisoner should be placed a full record 

 of its physical constants, such as mass, 

 density, electrical conductivity, specific 

 heat, etc., with a clear indication of what 

 is believed to be the probable accuracy of 

 such determination. 



