196 M. J. A. Groshans on the 



It follows from this that numerous analogous compounds 

 have the same value for x. In the following examples I have, 

 for the sake of conciseness, omitted the numerical data, giving 

 only the value of x deduced from the observed boiling- 

 points : — 



Examples of the Constancy of x. 

 («) Methylic and Ethylic compounds, with Oxygen, Sulphur, 

 Selenium, and Tellurium. 



(CH 3 ) 2 0, *=3. (C 2 H 5 ) 2 0, ff=5. 



(CH 3 ) 2 S, x=3. (C 2 H 5 ) 2 S, x=5. 

 (CH 3 ) 2 S 2 , x=3. (C 2 H 5 ) 2 S 2 , x=5. 

 (CH 3 ) 2 Se, x = Z. (C 2 H 5 ) 2 Se, x = 5. 

 (CH 3 ) 2 Te, x=3. (C 2 H 5 ) 2 Se 2 x=b. 



x in every case = ra. 

 (/3) Analogous compounds of Carbon and Silicon. 

 CC1 4 , x=2. 



SiCl 4 , x=%. (CH 3 ) 4 C *=6. 



CHC1 3 , x = 2. 

 SiHCl 3 , x=2. (CH 3 ) 4 Si, *=6. 



Here again # = m. 



(7) Analogous compounds of the members of the triad, Phos- 

 phorus, Arsenic, and Antimony. 



(CH 3 ) 3 P, «=5. PO(C 2 H 5 0) 3 , x=7. 



(CH 3 ) 3 As, x=5. AsO(C 2 H 5 0) 3 , x=7. 



PO(CH 3 0) 3 , x=5. PI 3 , x=7. 



AsO(CH 3 0) 3 .*=5. Sbl 3 , x=7. 



#=7, also for HgCl 2 , HgBr 2 , Hgl 2 , and Hg 2 I 2 . 



On the Temperatures T (273° -fS°) considered as proportional 

 to the Molecular Volumes of Substances in the Gaseous State 

 at the Boiling -point S°. 



We are accustomed to regard the absolute boiling-points 

 as quantities expressing degrees of heat, and this no doubt 

 they are ; but they are at the same time proportional to the 

 molecular volumes of the vapours, analogous to those of the 

 liquids at the boiling-point (v s = a/d 8 ). When the vapour- 

 density D 5 is expressed in terms of the volume of a gram of 

 water at 4° C, the absolute boiling-point T (affected by a 



