DEODORIZERS AND DISINFECTANTS. 
63 
opposite characters. The atmosphere, after it has passed 
over large towns, has been ascertained to contain but little 
ozonized oxygen, it having been used up in the destruction 
of those gaseous eliminations that are thence being constantly 
emitted. The same loss is sustained where large manu- 
factories exist, and during the prevalence of east winds there 
is a want of it. This conditional state of atmospheric 
oxygen is supposed to be brought about by the passage 
of electricity through the air, as during a thunder-storm, also 
by volcanic action, and the many chemical changes that are 
continually taking place on the earth’s surface, by which 
oxygen is liberated from its combinations, when it is in that 
form designated nascent. A larger amount is found to be 
existent in the summer season than in the winter, and it has 
been ascertained to increase in quantity above the sea-level ; 
simply because both at this time and place the corrective 
agent is most required. Herein w r e see proofs of wisdom 
and design in Creation. 
Lately, from the readiness w 7 ith which it yields up its 
oxygen, permanganic acid has been employed as a deodorizer 
in the form of permanganate of potassa; the permanganates, 
in solution, being decomposed by sulphuretted hydrogen, 
ammonia, &c. Other salts similarly constituted, may perhaps 
act in the same way. 
It has been stated that, if the vapour of creosote or chloro- 
form, coal gas, or carbonic or sulphurous acid, be mingled 
with oxygen, its action on organic bodies so as to cause their 
decay is checked by the setting up of a counter affinity. 
Absolutely pure oxygen, indeed, possesses preservative pro- 
perties, but when mixed with nitrogen, as in the atmo- 
sphere, then its tendency to bring about decomposition is 
great. 
In some cases, it is quite possible that this attractive or 
surface action, and slow combustion, are both in operation ; 
the retention of the substances by the former being neces- 
sary so that the latter may be effectually brought about. 
In like manner the soil exerts a purifying influence over 
<the water that percolates through it : and it is well it does 
so, or the soil would not be so fertile as it is ; while, as a con- 
sequence, the air would quickly become impregnated with 
putrid effluvia. Professor Way has ascertained that when 
solutions of the salts of ammonia, potash, magnesia, &c., are 
slowly filtered through dry soil, even if it be not more than 
a few inches in depth, the water that first passes through 
contains little or none of these salts. Even the drainage of 
a stable may be rendered comparatively pure by passing it 
