206 
Relation of Moisture in Air 
[April, 
ventilation, with the fullest admissions that in the quantities 
ever present in the living rooms, except by accident, it is 
quite harmless ; and, finally, its presence has been accepted 
as merely a measure of other more dangerous vitiations, in 
that as it is a definite product of respiration, and as the 
proportion present in any room, at a given moment, can be 
ascertained with tolerable exactness, an indication can be 
derived thereby of the extent of organic vitiation with some 
degree of certainty. 
The unquestioned theory of malaria, the meaning of 
which word can be extended to embrace diseases arising 
from deficient or defective ventilation, to-day, is organic 
vitiation, and the probability of this theory holding its place 
in future is, I think, a very fair one. The exhaled and 
exuded vapour from the human body is known to be laden 
with organic matter : much of this organic matter is within 
the range of the microscope, by means of which the local 
derivation of many particles can be determined ; but some 
of it is in the form of effluvia and odours, which pass the 
limits of visual observation in the smallness of the atoms, 
notwithstanding such effluvia or odours are decidedly per- 
ceptible to the sense of smell. With a dry external atmo- 
sphere and a reasonably free ventilation the exuded vapour 
and the organic matter pass away, or are diffused as rapidly 
as supplied. It should he remarked that the organic matter 
appears mainly to he in connection with the vapour in the air, and 
not to exist as a separate gas, diffused in the dry air when the 
vapour is removed hy natural causes. With an imperfedf or 
insufficient ventilation the upper parts of rooms become 
filled with air, which will be found to contain a much larger 
proportion of moisture than the lower portions, and wall be 
shortly found to be exceedingly offensive from the rapid de- 
composition which the exuded organic matter undergoes in 
a moist air. This will happen more frequently when the 
internal and external temperatures are about the same, and 
when it is so cold, raw, or windy as to require closed doors 
and windows, with only a small addition of heat, and when 
with these conditions the natural dew-point is high. These 
circumstances are in concurrence frequently in England, 
wEere probably 120 days out of 365 call for but small addi- 
tion of heat in rooms, while they rarely exist with us, the 
climate of our northern United State not giving 30 days in 
any year of similar kind. The objedfion of effluvia, which 
forms the distindfive one in audience-rooms in England, and 
is so noticeable to the American visitor of such rooms, is 
replaced in our halls by a simple sense of oppression — a 
