Manchester Memoirs, Vol. It. (1906), No. 2. 11 



" 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 an 

 " union of particles would have relations of infinity, and is 

 " therefore inconceivable, 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 of the infinitesimals in- 

 " volved in a centre of rotation, still less is it capable of 

 " comprehending the mode of union of the unknowable 

 " essences on which the physical qualities of chemical 

 " substances, after combination, depend. Philosophical 

 " chemists, I apprehend, will hereafter be able to refer the 

 " origin of the theory of the composite structure of matter, 

 " after chemical union, to the influence of ideas derived 

 " principally from the mechanical mixtures employed in 

 " pharmacy and in the culinary art." 



