2 76 Mr. J. J. Waterston on the Application of the Vapour -density 

 groupe HO. Les formules suivantes expriment ccs relations : 



C2R4 W 



c*Hn G2 



HH/ tf ' 



H j 



CI 



iate 

 lene. 

 ater. 



Expressed by the V.D. notation, the above reaction is 



1 »L glycol CH* Ot. HO* 1 = j CH» 0* . CI* H* { \-* «g 



1 mol. mur. acid. Cl'H a J l HO 2 1 moL vyate 



The reaction appears to be simply CI EP, driving out HO 2 

 and taking its place : both molecules have their elements in a 



burnt condition. To say that CI* takes the place of IP O 2 , is to 



convey the idea of CI* leaving the acid-molecule CI 2 H 2 , of which 

 there is no evidence. It is a mode of expression that I do not 

 think could be maintained if the potentialities of the phenomena 

 were kept in view ; yet it now pervades the writings of chemists. 



Pp. 419, 421. Action of per chloride of Phosphorus on Glycol. 

 — Muriatic acid vapour is given off, and there remains the chlor- 

 oxide of phosphorus and the Dutch liquid. " Ce chlorure prend 

 naissance en vertu de la reaction suivante 



€ 2 H 6 O 2 + 2PhCl 5 = C 2 H 4 CI 2 + 2PhO CI 3 + 2 HC1." 



Glycol. 



Chlorure 

 d' ethylene. 



By the V.D. notation the reaction is 



1 mol. glycol .{CH 2 0iH0* 



2 mols. perchlor. JP* 

 of phosph. (pi 



CI 



21 



fCH 2 Cllmol. chlor. ofolef. 

 P*Cl H 0*l2mol.ofchlorox. 

 P^ClHOaJ of phosphorus. 



Pi CI 2 * 



l U 



H*C1* 1 

 H*C1* J 



2 mols. muriatic 

 acid. 



The vapour- density of the perchloride of phosphorus, as mea- 

 sured by Mitscherlich, shows that although it boils at 82° C, it 

 is decomposed on rising into vapour, the one molecule, P* CI 2 *, 

 separating into two, viz. P^Cl 1 * and CI; so the above reaction 

 may admit of being represented as 



CH 2 0\HO^ 





fCH 2 Cl 



CI 





H^Cl* 



CI 



• = * 



H*C1* 



Pi CI 1 * 





pi C1 H o^ 



P1C1 U 





p£ cl H * 



