APPENDIX 109 



manganese and lead, etc., and ascribe to them the power 

 of oxylizing, not only one equivalent but the whole of the 

 oxygen with which they combine. 



A peculiar interest attaches to the relations which exist 

 between chlorine, bromine and iodine, the peroxides, and 

 the so-called hydracids of the halogens. The first class 

 of substances show a great similarity in their voltaic and 

 chemical behaviour, a similarity which would lead anyone 

 who studied them without regard to the current hypo- 

 theses to believe that they had a similar chemical constitu- 

 tion ; this, however, is completely contrary to our present 

 ideas. What strikes me as especially remarkable is the 

 following : When the hydracids of these three halogens 

 are mixed with the peroxides, chlorine, bromine and iodine 

 are liberated ; furthermore it is well known that chlorine, 

 for example, partially converts lead oxide into lead per- 

 oxide. In fact it is not improbable that chlorine is able, 

 when in contact with water, to produce some hydrogen 

 peroxide. Moreover we know that concentrated nitric 

 acid immediately liberates chlorine from hydrogen chloride, 

 and my latest investigations have shown that even a very 

 dilute solution of nitrous acid, when added to hydro- 

 chloric acid, at once sets chlorine free. My hypothesis 

 compels me to explain all these phenomena in a different 

 way from that in which they are explained by our present 

 theories. When aqueous rnurium oxide is brought in 

 contact with a compound containing oxylized oxygen, 

 such as lead peroxide, a part of the murium oxide unites 

 with the oxylized oxygen to form murium peroxide, 

 while the remainder of the murium oxide or hydrochloric 

 acid combines with the lead oxide to produce the so-called 

 lead chloride. Conversely when murium peroxide is 

 made to react with lead oxide, a portion of the latter will 



