443 



will hereafter be given in detail. I confine myself to a brief resume 

 of the conclusions. 



(1) * When an acid solution of permanganic acid is decomposed 

 by peroxide of hydrogen, the decomposition is in an invariable atomic 

 proportion, according to the equation 



Mn 4 7 + 5H 2 2 ==2Mn 2 + 5H 2 + 50 2 . 



(2) An alkaline solution of ferricyanide of potassium is reduced 

 by the peroxide of barium to ferrocyanide, with the evolution of 

 two atoms of oxygen, thus 



(3) An alkaline solution of hypochlorite of barium is reduced by 

 the peroxide of barium, according to the equation 



BaClO + Ba 2 O 2 + H 2 O=BaCl+2BaIIO + O 2 . 



A similar change takes place, as might be anticipated, with an 

 aqueous solution of chlorine in the acid solution of peroxide of 

 barium, but more slowly. I have elsewhere shown that the action 

 of iodine is expressed by the equation 



(4) The decomposition of chromic acid is of special interest. In 

 this case there are two distinct reactions, the first of which takes 

 place when chromic acid is in excess, according to the equation 



the second, which occurs when a large excess of peroxide of hydrogen 

 is present, and in which the peroxide of hydrogen loses exactly 

 double the amount of oxygen lost by the chromic acid, so that the 

 final result is expressed by the equation 



In the interval between these reactions the ratio of the loss of 

 oxygen from the peroxide to the loss from the chromic acid varies 

 between the limits 1 and 2 according to a definite law, being pro- 

 portional to the ratio of the masses of the substances employed. I 

 am able to show, by direct experiment, that the reaction between 



* This reaction has, I find, been published by Aschoff (see Repertoire de Chimie 

 Pure, August 1861, page 296). It was last year made the subject of a communi- 

 cation by me to the British Association, " On the Quantitative Estimation of the 

 Peroxide of Hydrogen." 



