No. 7.] WURTZ — THEORY 07 ATOMS. 389 



.lugmentation becoming very considerable, a change of condition, 

 solid becoming liquid, and liquid becoming gas; in the last, the 

 driving apart of the molecules is become immense in relation to 

 their dimensions. Thus acting on the atoms which compose 

 the molecule and amplifying their trajectories, heat can disturb 

 the equilibrium which exists in the system, causing a conflict of 

 these atoms with those of another molecule in such a way that 

 this disturbance or this conflict leads to fresh systems of equili- 

 brium, that is to new molecules. There commence the phenomena 

 of decomposition and dissociation, or, inversely, of combination, 

 which is the main spring of chemistry, and it is seen they are 

 but the continuation or consequence of the physical phenomena 

 we have just analysed, the same hypothesis, that of atoms, applied 

 to one and the other with an equal simplicity. 



I ask, will it not be easy to conceive that the physical and 

 chemical forces which act on ponderable bodies are applied also 

 to difi"use continuous matter in some way, and is it not natural 

 to suppose that there are limited and definite particles which re- 

 present the points of application of all these forces ? And this 

 view ought to apply to the two sorts of matter which form the 

 universe, ether and atomic matter, the one infinitely rarefied 

 but homogeneous, filling all space, and in consequence enormous 

 in its mass, both unseizable and imponderable ; the other non- 

 continuous, heterogeneous, and only occupying a very limited 

 portion of space, although it forms all worlds. 



Yes, it forms all worlds, and the elements of ours have been 

 discovered in the sun and in the stars. Yes, the radiations given off 

 by incandescent atomic matter which forms these stars are also, 

 for the most part, those which are produced by the simple bodies 

 of our planet. Marvellous conquest of physics which reveals at 

 oDce to us the abundance of forces which environ the sun and the 

 simplicity of the constitution of the universe ! 



A solar ray falls upon a prism and is turned aside in its path 

 and decomposed into an infinity of difi'erent radiations. These 

 take each a particular direction, and all range themselves in 

 bands in juxtaposition, and spread themselves out in the spectrum 

 if the light thus received and decomposed is thrown on to a 

 screen. The visible part of this spectrum shines with all the 

 colours of the rainbow ; but besides this, beyond both ends of the 

 coloured bands the radiations are not absent. The heat-rays can 

 be made to reveal themselves beyond the red ; the chemical rays, 

 Vol. VII. AA No. 7, 



