ORIGIN OF ELEMENTARY SUBSTANCES. 123 



weights. If, however, it be assumed that a particle of 

 hydrogen combines successively with one, two, three or 

 more of its own particles, to form the molecules H2, H3, 

 H4, H5, H6, H7, and that each of these molecules forms 

 the type of a group of elements under it, the intermediate 

 steps between the low atomic weight of hydrogen and 

 the high atomic weights of other elements are perceived, 

 and the different properties of elements of approximately 

 equal atomic weights admit of a rational explanation. 



Although it is herein assumed that hydrogen is the 

 ponderable base of all elementary species, it is probable 

 that this element itself, as further maintained by Prout, 

 may have been evolved from an ethereal substance of 

 much greater tenuity ■^. Further knowledge of the outer 

 regions of the solar atmosphere and of the zodiacal light 

 may possibly indicate the steps by which hydrogen was 

 formed. 



I would also observe that the term " molecule ^' is 

 here used only in the sense of a larger or denser particle 

 of matter, and does not imply the idea of a composite 

 aggregation of the separate particles, each preserving its 

 distinctive character after the molecule is formed, any 

 more than rain-drops preserve their distinctive character 

 after falling into the ocean. It appears to me much more 

 in accordance with the truth of nature to suppose that the 

 smallest conceivable particle of a chemical substance or 

 compound has the same physical properties absolutely as 

 the mass. If it be objected that such a union of particles 

 would have relations of infinity, and is therefore incon- 

 ceivable, it may be answered that the central particles of 

 a rotating body have mathematical and physical relations 

 of a similar kind, and as the instrument of thought is 

 incapable of forming a distinct conception of the magnitude 



* Prout's 'Chemistry and Meteorology,' 8tli Bridgewater Treatise, p. 130. 



