1902.] 



Per sulphuric Acids. 



97 



HO-SOo-OH 



HOSCVO 

 HO*S0 2 -6 . 



Sulphuric acid. 



Perdisulphuric acid. 



Disulphuric acid. Pertetrasuipliuric acid. 



afforded by solutions of Caro's acid will need to be verified, and cannot 

 be accepted as final until salts of the acid have been isolated. This 

 we are engaged in doing. 



Further consideration, in the light of the facts brought forward by 

 Baeyer and Villiger and in the present communication, of the results 

 arrived at by Lowry and "West, has served only to confirm the con- 

 clusion that the chief product of oxidation of sulphuric acid by 

 hydrogen peroxide in presence of less than 50 per cent, of water is an 

 acid richer in sulphur trioxide than perdisulphuric acid, and to justify 

 the assumption on which they based the formula HoS^Ou — namely, 

 that the acid is a member of the series HoOv/tSOs. Lowry and West 

 determined only the ratio of peroxide oxygen to persulphuric oxygen, 

 and paid no attention to the total oxidising power of the solution. 

 That they were justified in this course is apparent from the fact that 

 no change in the ratio of the two forms of oxygen was observed on 

 varying the strength of the peroxide solution from 10 to 40 " volumes," 

 nor was any change observed as the oxidising power gradually 

 decreased when the acid decomposed. 



If the main product of the interaction had been an acid of the 

 formula H0S0O9, this would not have been the case, as the equilibrium 

 represented by the equation 



would depend on the total oxidising power of the solution as well as 

 on the proportion of sulphuric acid and water; this is seen most 

 clearly when the equation of mass action, 



2H 2 2 + 2H 2 S0 4 = H 2 S 2 9 + 3H 2 

 C 2 C3 Ci 



KCo 2 C 3 2 = CA 3 , 



is transposed into the form 



H 2 



