Prof. Norton on Molecular Physics. 287 



ture of the permanent gases does not increase this value to the 



limit (4*93) at which the liquid state becomes possible.. 



The received theory among chemists, of combination by volume, 



is in entire accordance with these results derived from our theory 



of molecular forces, and with the conception to which we have 



been led of the constitution of simple and compound molecules 



(vol. xxx. p. 98, &c). If we suppose, with the chemists, that in 



general the ultimate molecule is composed of two ■• atoms," this 



is equivalent to saying, in the language of the present theory, that 



the ultimate molecule is a compound molecule consisting of two 



simple molecules united together, and provided with its own 



proper atmosphere. 



All such binary molecules of elementary gases will occupy, 



as we have seen, the same space, which may be called the unit 



of volume. If v represent any given volume, as a cubic inch, 



and n the number of atoms in v, then this unit of volume will 



v 

 be — Now, if one volume of one gas be presented to one volume 

 n o j. 



of another, the general result is that two volumes of a compound 

 gas are formed. This implies that each of the binary mole- 

 cules is decomposed, each atom of the one combines with one 

 of the other, and thus two new compound molecules are formed, 

 each occupying one unit of volume. If, as in the formation of 

 carbonic acid, one volume of one gas unites with one volume of 

 another, and one volume of compound gas is formed, we must 

 suppose that the two binary molecules unite, as wholes, and form 

 one new molecule containing four atoms associated in pairs. 

 Again, if, as in the formation of aqueous vapour, two volumes of 

 one gas combine with one of the other, and two volumes are 

 formed, we now have two molecules a and b combining with one, 

 c; c must be decomposed, and one of its atoms must combine 

 with a, and another with b : thus each molecule of water con- 

 tains two atoms of hydrogen, associated with one atom of oxy- 

 gen. If, as in the production of ammonia, three volumes unite 

 with one, and two volumes are produced, three molecules must 

 combine with one and two new compound molecules result. 

 This implies that the single molecule and one of the three mole- 

 cules are decomposed, and that the disunited atoms combine 

 with the other two. If the molecules of the two gases, or va- 

 pours, that combine be ever so complex, and the same number 

 of volumes unite as we have above supposed, with the same result 

 as to the number of volumes produced, the processes will be es- 

 sentially the same as just indicated. Each compound molecule 

 will occupy one unit of volume, whatever number of atoms, or 

 groups of atoms, it may contain, 



The decomposition of molecules which occurs in such cases 



