WAVES AND CORPUSCLES — DE BROOLIE 245 



small. The experimental knowledge of the corpuscular structure of 

 positive electricity is less direct; nevertheless, physicists have reached 

 the conviction that positive electricity is also subdivided into cor- 

 puscles, all the same in kind, and now called '' protons." The proton 

 has a mass, which, although very small, is nearly two thousand times 

 greater than that of the electron. Its charge is equal to that of the 

 electron but of contrary sign, positive instead of negative. 



Electrons and protons have extraordinarily small masses; never- 

 theless this mass is not zero and an enormous number of protons 

 make a total ma.ss of considerable amount. It is therefore tempting 

 to suppose that all material bodies, essentially characterized by 

 weight and inertia, in other words, by mass, are built of an enor- 

 mous number of protons and electrons. Looking at the matter in 

 this way, the atoms of which the elements arc composed and which 

 are the materials from which all boelies are constructed, must be 

 formed of protons and electrons. The 92 different atoms constitut- 

 ing the elements must be 92 different a.ssemblages of protons and 

 electrons. 



The idea that atoms are formed from electrons and protons has 

 been elaborated through the experimental work of the great English 

 physicist. Sir Ernest liutherford, and the theoretical studies of the 

 Danish scientist, Niels Bohr. The atom of a simple body is supposed 

 to be composed of a central nucleus carrying a positive charge equal 

 to a whole number X times the charge of a proton and N electrons 

 circulating about this nucleus. The assemblage is therefore electri- 

 cally neutral. Without doubt the nucleus itself is formed of protons 

 and electrons, the number of protons exceeding by N units the num- 

 ber of electrons. Almost all the mass of the atom is seated in the 

 nucleus since this contains the protons. The protons are far more 

 heavy than the electrons. The simplest atom is that of hydrogen. 

 It is made up of a nucleus containing a single proton with one elec- 

 tron revolving about it. 



What distinguishes the atom of one element from that of another 

 is the number N of elementary positive charges carried within the 

 nucleus. We can accordingly arrange these elementary bodies in a 

 series formed of increasing values of N from hydrogen (N = 1) to 

 uranium (N = 92). We may note that the order in which these 

 bodies fall in such an arrangement is precisely that which would 

 result from their atomic weights and chemical properties and which 

 is known as the Mendcleeff classification. 



I can not explain here in detail the idea that the atom is a kind 

 of solar system formed of protons and electrons as has been advo- 

 cated by the physicists. I will limit my.self merely to saying that 

 it allows the interpretation not only of the chemical properties of 

 the elementary bodies but also of a number of their physical prop- 

 28005—31 17 



