44 
CHEMICAL DISINFECTANTS. 
astrous Niger Expedition. It appears to have been exten- 
sively adopted by medical men. 
“ Another disease, namely influenza, has been imputed by 
high chemical authorities to the diffusion through the atmo- 
sphere of a peculiar gas. Dr. Prout regarding seleniuretted 
hydrogen as its cause, Schcenbein attributing its production 
to ozone. There is no evidence that either of these views is 
true, but much may be said in favour of the latter. The 
last severe epidemic of influenza spread over Europe with a 
rapidity which almost seems to point to a gas as the medium 
of its propagation. No one, however, has detected seleniu- 
retted hydrogen in the atmosphere ; and air largely impreg- 
nated with ozone, may be breathed with an impunity which 
throws great difficulties in the way of Schoenbein’s hypo- 
thesis. 
“Whilst thus, with the exception of influenza (if it is to be 
excepted), no gas is known to possess the power of develop- 
ing an infectious or contagious endemic or epidemic ; on the 
other hand, as Professor Graham has justly remarked, such 
infectious matters as are accessible to us ; for example, e the 
matter of cow-pox may be dried in the air, and is not in the 
least degree volatile. Indeed, the volatility of a body implies 
a certain simplicity of constitution and limit to the number 
of atoms in its integrant particle, which true organic bodies 
appear not to possess. Again, the source of such bodies 
being at all times inconsiderable, they w^ould, if vapours be 
liable to a speedy attenuation by diffusion, be so great as to 
render their action wholly inconceivable. It is more probable 
that matters of contagion are highly-organised particles of 
fixed matter, which may find its way to the atmosphere not- 
withstanding, like the pollen of flowers, and remain for a 
time suspended in it.’* 
“I shall refer to five of the disinfectants: 1, quicklime, 
including caustic potash and soda; 2, nitric acid ; 3, chlorine; 
4, aqua regia ; 5, ozone. The value of quicklime and of the 
caustic alkalis as disinfectants, has certainly not been ove- 
rated, although it may be questioned whether our sanitary 
authorities have been wise in trusting to lime alone as a 
purifier. From the careful study of the process of natural 
and artificial nitrification, and from the results of the appli- 
cation of soda-lime in organic analysis, w T e have learned that 
Elements of Chemistry, p. 336. 
