168 On Ozone and tts Relations to 
showed their capacity, when compared with the original 
intact substance, was considerably impaired for ozone. 
Any material alteration, moreover, in form or substance, 
causes a proportionate lessening of its power, and even the 
accumulation of suspended organic matter arrested in the 
process of filtration, or of gum and resin. on the surface, 
eventually determines a cessation of this property. 
But the affinity to which this is attributable: it consists 
of that of the second order necessary for chemical combi- 
nations, as first set forth, and the condition governing its 
action is, that the substance possesses a surface mechani- 
cally fitted for the reception and retention of oxygen. The 
oxygen thus situated seems to evince all the energy of 
combination, but lacking that force necessary for the con- 
stitution of a new form. The action of this induced 
oxygen lies only in proximity to the surface of the char- 
coal, or other ozonizable substance to which it owes its 
origin. For the purpose of calling its energy into play, 
actual contact is indispensable. This is illustrated very 
strikingly in the ensuing curious experiment.* If coarsely 
powdered animal charcoal be intimately mixed with small 
portions of phosphorus, the great oxidizing power of the 
charcoal quickly determines the combustion of the phos- 
phorus ; again, should an accidental scrap of iron find its 
way into charcoal used as a filtering medium, an occur- 
rence not uncommon, the metal becomes soon covered 
with a thick coating of oxide, which eventually cements 
charcoal and iron into a conglomerate mass. 
Oxide of iron in itself is an ozonizing substance; thus 
it is, that iron being a less oxidizable metal than zinc, be- 
comes converted into rust on exposure to the atmosphere, 
in a considerably shorter period of time than the latter 
metal, simply from the fact that the oxide regenerates 
ozone, and hence, continuously supplies the combining 
oxygen to the compound. Most acids are ozonizing 
bodies—that is, possess the power of generating ozone: 
by this means they determine the oxidation of the base 
with which they combine. Zinc and iron are slowly oxi- 
dizable in water, if devoid of acid; but in the presence of 
sulphuric or nitric acid, owing to the ozonizing effect of 
such on the oxygen of the water, speedily determines the 
oxidation of the metal, and forms a secondary compound 
salt. 
* Transactions of the Royal Institution, vol. 1 
