38 



Prof. A. W. Pucker on a Suggestion 

 Table II. 



I. 



II. 



III. 



IV. 



Y. 





Cp 



m-\-e. 



3n. 





CL 



1-286 ■ 



1-408 



1-131 



1-118 



1-097 



1-122 



1111 



1-098 



1-092 



1-089 



7 

 5 

 15 

 17 

 21 

 16 

 18 

 20 

 22 

 22 



6 

 6 

 24 

 15 

 24 

 12 

 12 

 15 

 15 

 15 



18 

 12 

 30 

 33 

 36 

 30 

 30 

 39 

 39 

 39 



HOI 



C 2 H 5 C1 



CHCI3 



2 H 4 01 . . . 

 POL 



AsCl 3 



SiCl 4 



SnCl 4 



TiCl 4 





The first Table contains a number of simple and more or 

 less complex compound gases and vapours ; the second is con- 

 fined to chlorine and its compounds alone. The difference 

 between the two is most marked. In the first the value of 

 m + e is for every substance (with one exception) less than 3n, 

 or than the maximum possible value of m. In the second the 

 reverse statement holds good in more than two thirds of the 

 whole number of cases. 



This difference can hardly be accidental ; nor can it be ex- 

 plained by an error of 6 per cent, in Regnault's experiments. 

 It might be accounted for by supposing that in the case of 

 chlorine e is abnormally large — and that this gas differs from 

 others in which the molecule is built up of two spheres, in that 

 the spheres are not necessarily in contact, and are probably 

 therefore less firmly united. 



Another supposition, however, would meet the case equally 

 well, viz. that n has been taken too small, that the symbol Cl 2 

 is incorrect, and that the atoms of chlorine, and therefore the 

 molecules of its compounds, contain a larger number of sub- 

 atoms or atoms than has been supposed. It need hardly be 

 added that this supposition fits in most satisfactorily with the 

 results of the recent researches of Prof. Victor Meyer on the 

 vapour-density of chlorine ; and in the fifth column of Table II. 

 are given the values of 3n calculated on the assumption that 

 throughout the first column we ought to write Cl 3 for 01. 

 Hydrochloric acid now offers a difficulty, as a body composed 

 of four spheres could only possess so small a number of de- 

 grees of freedom as five if the spheres were rigidly connected 

 with their centres in one straight line. With this exception, 

 however, columns III. and Y. of Table II. now present differ- 

 ences of the same sign and order as those in the corresponding 

 columns in Table I. 



The number of degrees of freedom attributed to each sub- 



