46 
CHEMICAL DISINFECTANTS. 
as being in all probability the great natural disinfectant. Its 
nature is still matter of speculation. Schoenbein, its dis- 
coverer, regards it as a peculiar oxide of hydrogen ; Berzelius 
and Faraday represent it as simply oxygen in a peculiar 
(or allotropic) state of modification; it has been suggested 
that it is an oxide of nitrogen; and quite recently M. Fremy 
has affirmed it to be what he calls f electrised oxygen,’ i. e. 
oxygen modified in properties by the action of electricity 
upon it ; a view not materially differing from that of Berzelius 
and Faraday. There are difficulties in the way of all these 
views, into which it is not necessary to enter. All that 
concerns our present subject is that, by different processes a 
substance can be developed in the atmosphere which possesses 
remarkable disinfectant and oxidising properties. The oldest 
known method of producing the so-called ozone, is the ex- 
posure of air to a stream of friction or high tension elec- 
tricity. Its odour may always be recognised in the neigh- 
bourhood of an electrical machine whilst at work. Another 
method is the galvanic decomposition of water, when the 
ozone accompanies the evolved oxygen. A third, and the 
most convenient method on the small scale, is the exposure 
of phosphorus in moist air. By these processes and by 
certain others, air is made to acquire a striking power of 
oxidising, bleaching, deodorising, and disinfecting. We can- 
not doubt that every thunder-storm developes some ozone, 
and other processes also probably produce it. At all events, 
the atmosphere frequently exhibits an oxidising and bleach- 
ing power, at other times absent, which Schoenbein, Faraday, 
and others, attribute to the development of ozone within it. 
6i The only antiseptics to which I shall refer are two. The 
first is sulphurous acid : it is a powerful antiseptic, for it 
resists thoroughly the decomposition or decay of organic 
matter. In reality, how r ever, it as much resists the develop- 
ment as the decay of organic bodies, and thus it doubly 
prevents the evolution of organic poisons. Dr. Christison 
long ago pointed out how r small a quantity of this acid is 
sufficient to destroy plants. In the wine countries it has 
been used from time immemorial to prevent the souring or 
acetification of the lighter wines, when kept in casks partially 
filled. Professor Graham, who strongly recommends it as a 
disinfectant, draws attention to the fact, that at Manchester 
the offensive effluvia of the cochineal dye-vats, which resist 
the action of chlorine and nitric acid, are at once destroyed 
by sulphurous acid. My own attention w r as directed to it from 
the employment of it on a large scale by paper-makers and 
others to secure the preparation of pure gelatine, a substance 
