110 Van Name and JIuf — Hydrolysis and Electrical 



reaction, furnishes an important argument in favor of 

 the double molecule. According to the formula assumed 

 this reaction may be written either 



(1) H 4 Po0 6 + H,0 = H3PO3 + H 3 P0 4 , or 



(2) 2H 2 P0 3 + H 2 == H 3 P0 3 + H,P0 4 , 



the former requiring that the reaction velocity in dilute 

 solution shall be proportional to the concentration of the 

 hypophosphoric acid, as we have found to be the case, 

 while the latter requires that the rate shall be propor- 

 tional to the square of that concentration. 



"While it is true that any molecular formula repre- 

 sented by an integral multiple of H 4 P 2 6 would also 

 account for the monomolecular reaction, the results of 

 molecular weight determinations by the freezing point 

 method 7 show that molecules containing four or six phos- 

 phorus atoms can hardly be present in any considerable 

 quantity, if at all. We are thus led to the conclusion that 

 the normal molecule of hypophosphoric acid in water 

 solution is that corresponding to the formula H 4 P 2 6 . 

 This conclusion can not be avoided by assuming that 

 these molecules, though present only in small amount, 

 are the more reactive, since in that case their concentra- 

 tion would be proportional to the square of the concen- 

 tration of the predominating H 2 P0 3 molecules, and the 

 reaction would appear to be bimolecular. It would, of 

 course, be possible to explain the facts by assuming that 

 the reaction was bimolecular but confined to one type of 

 molecule or anion whose concentration was proportional 

 to the square root of the total concentration, but this 

 hypothesis is arbitrary, and seems to be without rational 

 foundation. 



II. 



Conductivity. 



Measurements of the conductivity of hypophosphoric 

 acid have been made by Parravano and Marini, 8 using a 

 solution prepared by the action of hydrogen sulphide 

 upon lead hypophosphate suspended in water, and by 

 Rosenheim and Pinsker, 9 who worked with a solution 



7 Cornec, Comptes rendus, 150, 108, 1910 ; Kosenheim and Pinsker, Ber. 

 ehem. Ges., 43, 2010, 1910. 



8 Atti Acead. Lineei (5), 15, II, 203, 305, 1906. 

 •Ber. ehem. Ges., 43, 2003, 1910. 



