1 822 .] Properties of Peroxide of Hydrogen . 491 



and peroxide of copper, oxide of nickel, the protoxides of man- 

 ganese, iron, tin, cobalt, oxide of arsenic, and probably several 

 others, is requisite that the metallic oxide should be moist 

 or in solution : otherwise the oxygen would be disengaged, or 

 would remain in combination. It is moreover evident that iui 

 proportion as the new oxide is produced, it is possible that it may 

 expel a portion of the oxygen from the liquor, so that the action 

 may become complicated. 



Barj/tes. When barytes water is poured into concentrated 

 or diluted peroxide, a great number of brilliant scales are preci- 

 pitated ; these are merely hydrate of peroxide of barium, but if 

 barytes reduced to powder be used instead of barytes water^ 

 with shghtly diluted peroxide of barium, a violent extrication of 

 oxygen gas takes place, and much heat is excited. This heat 

 may be derived from the absorption of the water of the peroxide 

 by the barytes. As to the disengagement of the oxygen, it may 

 be attributed to the heat produced by the absorption of water, 

 and the formation of a small quantity of peroxide of barium : 

 hydrate of barytes possesses the power of evolving oxygen from, 

 the peroxide of hydrogen in all cases. 



Strontian. Strontian presents the same appearances with the 

 peroxide as barytes does. 



Lime. This base also produces with the peroxide of hydro- 

 gen, phenomena analogous to those which have been mentio-ned. 

 with the two precedmg bases. 



Hydrate of Copper. This hydrate, when mixed with the per- 

 oxide of hydrogen, becomes immediately a new oxide ol" an 

 ochre-yellow colour, and it rapidly evolves the oxygen of the 

 peroxide v/hicli remained undecomposed. When the peroxide 

 is concentrated, the action is vivid, there is disengagement of 

 heat, and it requires much to convert all the oxide of copper into 

 peroxide. In order that the peroxidation may take place, it is 

 not only requisite that the peroxide of hydrogen should be 

 diluted with water, but other circumstances hereafter to bemepb- 

 tioned must be attended to. 



Calcined Peroxide of Copper. In this state the oxide of copper 

 cannot of course combine with more oxygen ; it produces a very 

 evident effervescence of oxygen gas when put into peroxide of 

 hydrogen. 



Hydrate of Zinc. The same as copper : this oxide becomes a 

 peroxide with oxygenated water, so that very, littie oxygen is 

 evolved. 



Oxide of Zinc by Calcination. More converted into peroxid<y 

 than in the former case ; the evolution of oxvgen gas is extremely 

 slight. 



Hydrate of Nickel. This is another oxide, which-, with th^ 

 peroxide of hydrogen, probably forms a new oxide ; it also occa- 

 sions a slight disengagement of oxygen. 



ISlew Series, vol. iii. p: 



