THEIR CAUSE. 223 



the component parts are in a state of such ten- 

 sion, that the least disturbance overcomes their 

 chemical affinity. They exist only by the vis 

 inertia, and any shock or movement is sufficient 

 to destroy the attraction of their component parts, 

 and consequently their existence in their definite 

 form. 



Peroxide of hydrogen belongs to this class of 

 bodies ; it is decomposed by all substances capable 

 of attracting oxygen from it, and even by contact 

 with many bodies, such as platinum or silver, which 

 do not enter into combination with any of its con- 

 stituents. In this respect, its decomposition depends 

 evidently upon the same causes which effect that 

 of iodide of nitrogen, or fulminating silver. Yet it 

 is singular that the cause of the sudden separation 

 of the component parts of peroxide of hydrogen 

 has been viewed as different from those of common 

 decomposition, and has been ascribed to a new 

 power termed the catalytic force. Now, it has not 

 been considered, that the presence of the platinum 

 and silver serves here only to accelerate the decom- 

 position ; for without the contact of these metals, 

 the peroxide of hydrogen decomposes spontane- 

 ously, although very slowly. The sudden separa- 

 tion of the constituents of peroxide of hydrogen 

 differs from the decomposition of gaseous hypochlo- 

 rous acid, or solid iodide of nitrogen, only in so 

 far as the decomposition takes place in a liquid. 



A remarkable action of peroxide of hydrogen has 



