251 THE NUMERICAL EELATION 



that the classification here offered, and the numerical law here explained, may be ex- 

 tended to all compounds. The elements of any one series, by combining, give rise to 

 perfectly parallel series of homologous binaries, some of which are given in the table. 

 The binaries of those series which have the greatest common difference are generally 

 acids ; and of those which have the smallest, they are generally bases. These acids and 

 bases unite together and form series of homologous salts. As in Organic Chemistry, 

 many of the series are very incomplete ; but they are much more generally perfect 

 than in that newer department of the science, and almost every day fills up some gap. 



It will be seen, then, that not merely a plan has been given for classifying the ele- 

 ments, but one which will also embrace all inorganic compounds, and affiliate with the 

 similar classification which has already been established in Organic Chemistry. We 

 have not attempted to develop such a classification, since to do it Avould require a vol- 

 ume ; nor is it necessary, as any one can develop it for himself. 



That the atomic weights of the series of homologous compounds follow the same 

 numerical law as those of the elements is easily shoAvn. Take as an example the series 

 of salts homologous with KO, NOj, which may be expressed in general by KO, RO5, 

 where R is any member of the Six Series after Oxygen, and whose atomic Aveight, 

 therefore, equals 8 + w 6. The atomic weight of KO, RO5 must be necessarily 

 39.5 + 48 + (8 + M 6), or 95.5 + n 6. As this symbol difi"ers from that of the Six 

 Series only in the nucleus, the atomic weights of the salts which are represented by it 

 must progress by the same differences as those of the corresponding elements. 



The properties of these series of homologous compounds Avill also be found to vary 

 in a regular manner, and the law of the progression of the specific gravities in the 

 gaseous state can be easily expressed algebraically, since in each series the quotient of 

 the specific gravity divided by the atomic Aveight is a constant quantity. As an illus- 

 tration, we may take the series of binaries homologues of Avater giA'en in the Nine 

 Series of our table. It folloAvs from AA'hat has been said, that the atomic Aveights of 

 these compounds equals 9 + w 9. With each ^—^ = 2, therefore Sp. Gr. = 4.5 + n 4.5. 

 We giA'e below a table of the observed or calculated specific gravities, not only of 

 these compounds, but also of- those homologues of NH3 whose specific graAdty has 

 been observed. 



