CHEMICAL SCIENCE. 201 



the ferro-sesquicyanuret of potassium the peroxide of barium, a similar 

 reaction takes place, Prussian blue, nitrate of baryta, etc., being formed, and 

 inactive oxygen eliminated. From these facts it appears that, under certain 

 conditions, even peroxide of iron and HO? or Ba02 are capable of catalyzing 

 each other into FeO and HO, or BaO and 0. 



5. Under certain circumstances, Pb02 or Mn02 are soluble in strong acetic 

 acid; now, if you add to such a solution HOs or BaOs, the peroxides will be 

 reduced to HO or BaO, and PbO or MnO, inactive oxygen being disengaged. 



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C. It is a well-known fact, that the oxide of silver = Ag ( O), or the 



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peroxide of that metal = Ag ( 0)2, and the peroxide of hydrogen = 



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HO + (+O), catalyze each other into metallic silver, water, and inactive 



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oxygen. Other ozonids, such as PbO + ( O) or MnO + ( O), on being 



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brought in contact with HO + (+O), are transformed into PbO or MnO, 

 HO and 0. Xow the peroxide of barium = BaO + (+ O), acts like HO + 



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(+O). If you pour water upon an intimate mixture of AgO, or AgO 2 and 

 BaOs, a lively disengagement of inactive oxygen will ensue, AgO, AgO2 and 

 BaO:> being reduced to metallic silver and baryta. In concluding the first 

 part of my letter, I must not omit to state the general fact, that the oxygen 

 disengaged in all cases of reciprocal catalysis of oxy-compounds, behaves in 

 every respect like inactive oxygen. 



There is another set of chemical phenomena, in my opinion closely con- 

 nected with the polar states of the active oxygen contained in the two oppo- 

 site classes of peroxides. It is known that a certain number of oxy-com- 

 pounds, for instance, the peroxides of manganese, lead, nickel, cobalt, 

 bismuth, silver, and also permanganic, chromic, and vanadic acids, furnish 

 with muriatic acid chlorine, whilst another set, such as the peroxides of 

 barium, strontium, potassium, etc., are not capable of eliminating chlorine 

 either out of the said acid or any other chlorid. This second class of oxy- 

 compounds produces, however, with muriatic acid, the peroxide of hydro- 

 gen; and it is quite impossible in any way to obtain from the first class of 

 the peroxides HO 2 , or from the second chlorine. 



You are aware that, from reasons of analogy, I do not believe in the doc- 

 trine of chlorine, bromine, etc., being simple bodies, but consider those 

 substances as oxy-compounds, analogous to the peroxides of manganese, 



lead, etc., in other terms, as " ozonids." Chlorine is, therefore, to me the 



o 

 peroxide of murium = MnO + ( O), hydrochloric acid = MuO + HO, and, 



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as already mentioned, the peroxide of barium = BaO + (+ O), that of hydro- 



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gen HO + (+ O), and the peroxide of manganese = MnO + ( O). Pro- 

 ceeding from these suppositions, it is very easy to account for the different 

 way in which the two sets of peroxides are acted upon by muriatic acid. 

 From reasons as yet entirely unknown to us, HO can be chemically asso- 



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ciated only with + O, and with no other modification of oxygen, to consti- 

 tute what is called the peroxide of hydrogen; and in a similar way MuO (the 



hypothetical!}' anhydrous muriatic acid of older times) is capable of being 

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united only to O, to form the so-called chlorine which I denominate por- 



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oxide of murium. If we cause MuO + HO to react upon BaO -f- (+O), 

 MuO unites with BaO, and HO with -f-O; but if you bring together MuO -J- 



