362 



metal, and the hydrated and anhydrous acetic acid corresponding to 

 the hydrated and anhydrous oxide. These investigations have been 

 succeeded by others, which have had their origin in the consistent 

 development of these ideas. The following discovery extends and 

 completes these analogies. I have to add a new term to this series, 

 of which hitherto no analogue has existed. This term is the per- 

 oxide of the organic radical, the body which in the series of acetyl 

 corresponds to the peroxide of hydrogen or barium in the series of 

 the metal. Of these remarkable substances I have prepared two, the 

 peroxides of benzoyl and of acetyl ; but the method by which these 

 are procured is doubtless of extensive application, and we may con- 

 sider ourselves as in possession of a class of bodies of a new order, 

 the study of which cannot fail greatly to extend our knowledge. 



These peroxides are prepared by the action of the anhydrous acid, 

 or the corresponding chloride, upon the peroxide of barium. It is 

 first necessary to prepare this peroxide in a pure condition. This is 

 effected by precipitation of the solution of the peroxide of barium in 

 hydrochloric acid by baryta water, and by drying in vacuo the pre- 

 cipitate thus obtained. The peroxide of barium thus procured is 

 perfectly pure, with the exception of a trace of carbonate. In ap- 

 pearance it resembles magnesia. 



To prepare the peroxide of benzoyl, the chloride of benzoyl and 

 the peroxide of barium are taken in equivalent proportions and mixed 

 in water. A mutual decomposition takes place ; and a substance is 

 formed which, after crystallization from anhydrous ether, gave the 

 following results to analysis : 



Carbon 69'23 



Hydrogen 4*10 



Oxygen 26'67 



100-00 

 The calculated numbers for the peroxide of benzoyl are 



C 14 168 69-42 



H 10 10 4-13 



O 4 64 26-45 



242 100-00 



This substance contains an atom of oxygen more than the anhy- 



