240 THE NUMERICAL RELATION 



the explanation accompanying the table. That the properties of these elements vary 

 as we descend, can be easily shown. Oxygen is a permanent gas, as is also Fluorine. 

 Cyanogen is a gas, but may be condensed to a liquid. Chlorine, a gas also, can be 

 condensed more easily than Cyanogen. Bromine is a fluid at the ordinary tempera- 

 ture ; and, finally, Iodine is a solid. Moreover, starting from Cyanogen, the solubility 

 of these elements in water decreases as we descend in the series; and, again, the 

 specific graA-ity of their vapors follows the inverse order of progression, gradually 

 increasing from Oxygen down. The atomic weights vary in the same order, and 

 admit of a general expression, which is 8 + n 9, or, in other words, the diff'erences 

 between the atomic weights of these elements are always a multiple of nine. This 

 general formula may be said to represent the constitution of these elements, in the 

 same way that the symbol (C^H) O3, HO -f n (C2H2) represents the composition of the 

 volatile acids before mentioned. In the place of {CJl) O3, HO we have 8=0 = the 

 weight of one atom of Oxygen, and in the place of C^Ha we have nine. What it is 

 that weighs nine (for it must be remembered that those numbers are weights) we can- 

 not at present say, but it is not impossible that this will be hereafter discovered. In 

 order to bring the general symbol of the volatile acids into exact comparison with 

 that of the Nine Series, we must reduce the symbols to weights, when the two formulse 

 become 



46 + n 14, where 46 = (C^H) O3, HO and 14 = C^H, ; 



and 8 + « 9, where 8 = and 9 = x. 



The numbers 46 and 14 are known to represent the weights of aggregations of atoms. 

 The number 8 represents the weight of one Oxygen atom, but we cannot as yet say 

 what the 9 represents. After this comparison, it does not seem bold theorizing to 

 suppose that the atoms of the members of this series are formed of an atom of Oxy- 

 gen as a nucleus, to which have been added one or more groups of atoms, the weight 

 of which equals nine, or perhaps one or more single atoms each weighing nine, 

 to which the corresponding element has not yet been discovered. As it will be con- 

 venient to have names to denote the two terms of the formulae which represent the 

 constitution of the different series, we will call the first term, in accordance with this 

 theor)-, the nucleus, and the number in the second term multiplied by n the common 

 diff^erence of the series. 



From what has been said, it will be seen that the idea of the classification is that 

 of the organic series. It is in this that the classification diff'ers from those which 

 have preceded it. Other authors, in grouping together the elements according to the 

 principles of isomorphism, have obtained groups very similar to those here presented. 



