Multiple Proportions of the Atomic Weights. J^ 



bility that all the theoretic atomic weights in this series are 

 correct. 



While the atomic weights of the series H4/Z, H6n, Hyn, 

 are multiples of their typical molecules, their other numerical 

 relations differ from those in the preceding series. The 

 possible causes of this departure from the simple law 

 observed in the other series I have briefly stated in my 

 former paper, and will only make mention of the two 

 missing members of H47Z with atomic weights = 16 and 32 

 and the missing members of ¥L6n in homologous positions 

 with atomic weights =18 and 36, which I suggested may 

 have been transformed into the negative forms of the series 

 H2« and Hn respectively. I will, however, again direct 

 attention to the present unsatisfactory state of our know- 

 ledge respecting the atomic weight of silicon. The wide 

 diffusion of this element in nature, constituting as it does, 

 in combination with oxygen, more than one half of the 

 earth's crust, makes it hardly creditable to the chemical 

 science of the present day that there should be doubts respect- 

 ing its atomic weight and position in the classification of 

 elementary substances. 



Silicon in my table is the second member of Hyn with 

 an atomic weight = 35 and forms with nitrogen and iron a 

 triad similar to the first three members of Hn, H27Z, H^n, 

 Hs«. 



The position of Si = 35 as the second member of the 

 series not only throws new light on the disputed atomicity 

 of this element, but also explains the anomalous atomic 

 heat which has been assigned to it. 



Since the investigation of the properties of silicon by Ber- 

 zelius, who regarded silicic acid as a trioxide, much discussion 

 has arisen as to whether the .atomic weight of silicon should 

 be 21 or 28 ; or the formula for its oxide Sia0 3 or Si0 2 . 

 Chemists are now generally agreed upon the latter formula 

 for silicic acid, and have accordingly classified silicon with 



