

Theory of Molecular Volumes. 355 



Phosphorus P. 



Trivalent P is certainly found in 



P01 3 , PBi- 3 , C H 5 -PC1 2 , 

 and its volume therein is 27*1. 



V PC1 3 93-34, P = 93-34-3x22'l = 27-04. 

 Pentavalent P occurs in 



0=P=C1 3 , S=P = C1 3 , = P = Cl 3 Br. 

 CI 



I C 2 H,3 ... 48-0 



CVE 5 -P = PO(27-l + 8'3) 35-4 



2C1 ... 44-2 



01 



2A.V. 127-6 Obs. 128-6. 



P has the same value as pentavalent P. 



The two extra valencies appear to have a different value in 



PC1 5 , V 128-9 (Prideaux). 



POI3 93-4 (Thorpe), 2 01 44-2, 2A.V. 137-6 A 



Observed 128'9 ~" 8 ' 7 



So also in PBr 5 , V 157'3 (Prideaux). 



PBr 3 108-3 (Thorpe), 2 Br 57*0, 2A.V. 165*3 



Observed 157-3 "" 8 *° 



The difference is nearly the same in the two cases, and 

 might be explained by assuming the possession o£ ring- 

 structure : — 



1 

 CI CI ' < ,Br = Br 



P /' Cl or Br— P I 



CI ,^Q\ X Br 4= Br 



This would also explain the instability of these compounds 

 or liability to dissociation. 



PC1 S =PC1 3 + C1 2 



for the double bond is essentially weak. 



Again, in molecules P 4 6 P 3 4 ring structure is present 



2 A 2 



