286 INTRA-ATOMIC ENERGY. 



rarefied, gases traversed by an electriv- discharg-e, the same gas. nitro- 

 gen, for example, may give different spectra, according to the degree 

 of the vacuum.. 



Carrying, then, his investigations to the stars, the same astronomer 

 showed that the whitest ones — whicli are also the hottest, as is proved 

 by the prolongation of their spectrum into the ultra violet — are com- 

 posed of only a very small number of chemical elements. Sirius and 

 «'-Lvra, for example, are composed almost exclusively of hydrogen. 

 In the red and yellow stars, which are less hot, having begun to cool, 

 and therefore are older, we see the other chemical elements succes- 

 sively appear. First, magnesium, calcium, sodium, iron, etc., then 

 the metalloids, the latter l)eing seen only in the earliest stars. It is, 

 therefore, only as their temperature lowers that the elements of the 

 atoms can group themselves so as to form the elementary ])odies. 

 Sir Norman Lockyer finall>' arrives at the following conclusion: 

 "The chemical elements are, like plants and animals, the product of 

 evolution." 



The preceding ol)servations seem to definitely prove, conforma])ly, 

 indeed, to one of the oldest theories of chemistry, that the various ele- 

 mentar}" l^odies were derived from a single sul)stance. Hypothesis 

 begins only when we suppose that this priniitive substance was pro- 

 duced by a condensation of the ether. 



It appears dou])tful whether heat was the only cause of the trans- 

 formation of atoms. Other iniknown forces nnist, pro])ably, have 

 acted. What these forces were is, however, of no consequence; the 

 essential fact is that observation of the stars shows us the evolution of 

 atoms and the formation of various bodies under the influence of that 

 evolution. 



M(>l>'dity and sensitiveiieKft of inatter. — We have now reached that 

 phase of the history of atoms in which, under the influence of unknown 

 causes whose effects only we can ascertain, they have finally' formed 

 the various elementary bodies that make up our globe and all the 

 beings that live upon its surface. Matter is born and will persist 

 during a long succession of ages. ■ 



It persists with various characteristics, of which the most marked 

 appears to be the stability of the atoms that compose it. They serve 

 to form chemical structures whose form readily varies but whose mass 

 remains practically invariable throughout all changes. 



The materials of the chemical structures are then vei'y stable. l>ut 

 these structures are sometimes of very great fragility and always of 

 extreme mobility. The least variations of the environment — tempera- 

 tiu'e, pressure, etc. — instantl}' modify the movements of rotation and 

 oscillation of the atoms of which matter is made up. 



These luodifications are rendered easy by the gramilar state of mat- 

 ter. We are obliged to admit, in fact, that the atoms that compose it 



