CHEMICAL DISINFECTANTS. 
43 
include all the known or supposed causes of the development 
of disease, which are referred to under the names of miasma, 
malaria, infectious virus, contagious matter, & c. 
“ An antiseptic is an agent which prevents or arrests the 
development of organic poisonous (or non-poisonous) matter 
without effecting its chemical decomposition. 
“A deodoriser is a substance which destroys odour, by 
decomposing or combining with, or absorbing odorous mat- 
ter. Chlorine, for example, decomposes sulphuretted hy- 
drogen, whilst a salt of lead decomposes it, and charcoal 
simply absorbs it. 
“ Before considering the relative merits of particular sub- 
stances belonging to these classes, it is necessary, however, 
briefly to discuss the important question — does the poisonous 
organic matter which occasions certain diseases, occur in the 
solid, liquid, or gaseous form? The certainty that prolonged 
exposure to a vitiated atmosphere, such, for example, as that 
of a fever ward, produces disease, has led to a conclusion in 
which probably all concur, that the air is one of the chief 
media through which disease is propagated, and this connec- 
tion has in turn led to the much more doubtful inference that 
infectious matter is truly gaseous or vaporous. This view 
has probably been strengthened by the recent extensive study 
of the properties of anaesthetics, and by the many observa- 
tions which have been made on the rapid and powerful action 
on the body of substances which enter it through the lungs. 
It has certainly also been deepened by the opinion, widely 
prevalent, that the gases which are evolved from cesspools, 
sewers, and stagnant waters in general, particularly sulphu- 
retted hydrogen, hydrosulphuret of ammonia, and marsh gas 
(light carburetted hydrogen) are the direct and specific causes 
of ague and fever. 
“If this opinion were well founded, the limits and best modes 
of applying disinfectants could be determined without much 
difficulty, and our control over infectious diseases would 
certainly be much greater than it is. 
“ I think, however, that we may with confidence affirm that 
the great majority of diseases are not propagated by gaseous 
poisons. The recent tendency to advocate an opposite 
opinion, has been mainly occasioned, I believe, by an opinion 
expressed by the late Professor Daniell, to the effect that the 
fatal fever of the African coast is occasioned by sulphuretted 
hydrogen. This view was founded on an analysis of water 
brought from that coast, and determined the ventilating 
arrangements fitted up in the vessels which formed the dis- 
