07t the Peroxide of Hydrogen, 37 



of oxygen, than the metal has, the liquid becomes negative, thus ac- 

 ting the part of the copper plate of a battery, while the metal be- 

 comes positive, supplying the place of the zinc plate. The liquid isi 

 thus resolved into water and oxygen. If the metal be very oxyda- 

 ble, it retains the oxygen, which is evolved if gold, platina, he. be 

 used. We need scarcely refer to the wires of a battery, for a paral- 

 lel case. 



When the peroxide of hydrogen comes in contact with the oxide 

 of silver, the oxygen escapes from both, and the latter is reduced to 

 the metallic state. To comprehend this most singular fact, it must 

 be remembered, that metals combine, under certain circumstances, 

 witli more oxygen than under other circumstances ; and it must be 

 especially recollected, that when the peroxide of potassium is placed 

 in water, it gives off oxygen, and becomes a protoxide. It is not 

 ^oing too far then, to suppose that a peroxide may result from the ac- 

 tion of the peroxide of hydrogen on the oxide of silver, that this 

 peroxide exists under no other circumstances, and is, like the perox- 

 ide of potassium, decomposed by water. The conclusion will, per- 

 haps, warrant this assumption. The oxide of silver, then, being put 

 into the peroxide of hydrogen, the latter having no affinity for oxy- 

 gen, becomes negative, while the former, becoming positive, receives 

 oxygen, and becomes a peroxide, to which the excess of oxygen 

 must adhere very slightly. But the fluid in immediate contact with 

 this peroxide has, by yielding its oxygen, been converted to water ; 

 and we have, now, in contact, not peroxide of hydrogen and protox- 

 ide of silver, but protoxide of hydrogen and peroxide of silver. The 

 effect is, a total change in the electrical phenomena. The peroxide 

 of silver becomes negative, and the protoxide of hydrogen positive. 

 This galvanic influence forces the silver to reject the whole of the 

 oxygen, returning to the metallic state ; hence results the incorrect 

 opinion, that the oxide of silver has decomposed the liquid, without 

 receiving oxygen ; while, in reality, it has only received oxygen at 

 one moment, to change its electricity, and reject it in the next instant. 

 The same effect is produced by other oxides reducible by heat alone ; 

 the oxide being reduced to a metallic state. 



Those protoxides which are not reduced by heat alone, become 

 peroxides ; and these peroxides are not reduced to a metallic form, 

 as in the above cases, because the galvanic effect produced by their 

 contact with water, is too slight. In this respect, they differ from the 

 peroxide of potassium, and the (supposed) peroxides of silver, gold, 

 he. which cannot exist in water. 



