THE PROGRESS OF SCIENCE 



519 



heavy apparatus room, a room equipped I 

 for low-temperature work, the machine ; 

 shop and a kitchen. On the first, the ; 

 main floor, are located the general office, ' 

 the directors' suite, the office of the edi- 

 torial department, the library, the office 

 and laboratory of the assistant direc- 

 tors, the assembly hall, a special appa- 

 ratus room and a dark-room laboratory. 

 The second and third floors each con- 

 tain ten large research laboratories and 

 nine small ones; the fourth floor, which 

 is not finished, will contain an identical 

 number of laboratories as soon as the 

 growth of the institute warrants its 

 completion. At the present time twenty- 

 three fellowships are in operation and 

 forty research chemists are engaged in 

 a study of the variety of industrial 

 problems under investigation at the in- 

 stitute. 



ATOMISM IN MODEBN PHYSICS 



In an address at the spring meeting 

 of the National Academy of Sciences, 

 Dr. E. A. Millikau, of the University of 

 Chicago, reviewed the discoveries of 

 the newer physics. In abstract he said: 



Atomism in modern physics begins 

 with Dalton's discovery in 1803 of ex- 

 act multiple relationships between the 

 combining powers of the elements. Out 

 of this discovery grew the whole of 

 modern chemistry. The second tre- 

 mendously important step was taken vn 

 1815 when Prout pointed out that the 

 atomic weights of the lighter elements 

 appeared to be exact multiples of that 

 of hydrogen, thus suggesting that hy- 

 drogen was itself the primordial ele- 

 ment. The periodic table of Mendeleef 

 added support to such a point of view, 

 and Moseley's recent brilliant discovery 

 through the study of X-ray spectra of a 

 new series of multiple relationships, 

 represented by a consecutive series of 

 atomic numbers from 13 up to 79 with 

 every number except three correspond- 

 ing to a known element, is another most 

 significant bit of evidence. When we 

 add to this three other facts, namely, 

 (1) that each member of a radioactive 

 family, like the uranium family, has 



been definitely shown to be produced 

 from its immediate ancestor by the loss 

 by that ancestor of one atom of helium 

 (which is almost equal in weight to 

 four atoms of hydrogen), (2) that in 

 an atomic weight table the differences 

 between the weights of adjacent ele- 

 ments are in almost every case exact 

 multiples of the weight of the hydrogen 

 atom, the characteristic helium differ- 

 ence 4 appearing with extraordinary 

 frequency, and (3) the fact that the 

 introduction of the concept of electro- 

 magnetic mass, and the consequent dis- 

 covery of the inconstancy of mass, op'in 

 several ways of explaining the slight 

 departures in the exactness of the mul- 

 tiple relations between atomic weights 

 pointed out by Prout, it will be evident 

 that modern science may well feel fairly 

 confident that it has indeed found in 

 hydrogen the primordial atom which 

 enters into the structure of all the ele- 

 ments. All this is merely a very mod- 

 ern verification of very ancient points 

 of view. 



But modern physics has recently 

 taken a more significant and more 

 fundamental step than this, for it has 

 looked inside the atom with the aid of 

 X-rays and other ionizing agents, and 

 has there come upon electrically charged 

 bodies, whose inertia or mass is wholly 

 accounted for, at least in the case of 

 the negative elements, by their charges 

 This discovery marks the fusing into 

 one another of two streams of physical 

 investigation, namely, the molecular 

 stream and the electrical stream. A 

 necessary condition for the justification 

 of this last step was the bringing for- 

 ward of indubitable proof that the 

 thing which has heretofore been called 

 electricity is after all, contrary to 

 Maxwell 's view, a definite material sub- 

 stance in the sense that it exists in 

 every charge in the form of discrete 

 elements; in other words, that it too 

 like matter is atomic or granular in 

 structure. Such proof was found "^n 

 the discovery in the oil drop experi- 

 ments of even more exact multiple re- 

 lationships between all the possible 



