46 POPULAR SCIENCE MONTHLY 



of this energy which we observe, and for the length of time during 

 which it must have been given off according to the evidences of geology. 



There is no chemical reaction which is not hastened or retarded 

 by a change in temperature. In general, the velocity of a chemical 

 reaction is increased by an elevation of the temperature and diminished 

 by a reduction of the temperature. But radium compounds emit their 

 rays undisturbed, at an even, unaltered rate, whether they be heated 

 to a high temperature or cooled by immersion in liquid hydrogen and, 

 what is perhaps equally striking, whether they are in the solid state 

 or dissolved in some solvent. 



In view of such facts as these, it is idle to suppose that radium is 

 an unstable compound decomposing into its elements, using the terms 

 compound and element in their usual sense. Conflict as it may with 

 preconceived opinions, we seem forced to concede, not only that the 

 transmutation of the elements is possible, but also that these trans- 

 mutations are going on under our very eyes. 



As has already been pointed out, this does not mean that we shall 

 shortly be able to convert our elements into each other. Far from it, 

 up to the present time we have not the slightest idea how to initiate 

 such a process nor how to stop it. We can not, by any means known 

 to us, even alter the rate at which it proceeds. 



Now how shall we fit all these new facts and ideas in with our old 

 ones regarding the elements and atoms, and how many of the old ideas 

 must be discarded? Brief consideration is enough to convince us that 

 very few of the old ideas, in fact none of value, need be sacrificed. We 

 must indeed grant that Dalton's fundamental assumption is false, that 

 the atom, in spite of its name, is divisible, and consequently that our 

 elements are not our simplest substances, but decidedly complicated 

 complexes. But all the facts included in the laws of definite and 

 multiple proportions remain fixed and reliable, as indeed must all facts, 

 expressions of actual experimental results, no matter what else varies. 

 And there is not the least necessity for altering the methods of using 

 atomic weights in calculations, nor for ceasing to use structural dia- 

 grams and models for molecules. We must merely modify our ideas 

 and definition of an atom, and this modification is in the direction of 

 an advance. We know more about an atom, or think we do. 



Assume the inferences from the evidence just reviewed to be correct, 

 and how do they affect our conception of the atom? First of all, our 

 smallest, lightest, simplest atom, that of hydrogen, becomes an aggrega- 

 tion of about eight hundred smaller particles or corpuscles, and the 

 atoms of other elements become aggregations of as many corpuscles as 

 are obtained by multiplying the atomic weight of the element by eight 

 hundred. Thus the atom of mercury must be thought of as containing 

 800 times 200, or 160,000, corpuscles. Next, the methods by which we 

 believe we can calculate the approximate size of atoms and corpuscles 



