VENTILATION. 
absorption through the skin. The combinations 
of sulphur, phosphorus, and nitrogen with hy- 
drogen, are fully sufficient to explain the fetor 
of animal exhalations. The deadly poisonous 
sulphuretted hydrogen is largely emitted by 
some persons in a state of disease, especially by 
those who have undergone excessive mercurial 
treatment. As it blackens white lead, the ap- 
pearance of discoloration on the white paint of 
a room pretty surely indicates, in the absence of 
any other apparent cause, an excess of this gas 
from some individual who has occupied or vi- 
sited the apartment. The same compound black- 
ens the trinitrate of bismuth, from which the 
pearl powder of the shops is manufactured. La- 
dies using this pigment upon their skin should 
ascertain that they are free from an abnormal 
generation of sulphuretted hydrogen; otherwise 
the pearl powder may change from white to a 
livid lead colour, or even black,—an effect often 
unjustly attributed to the bad quality of the 
article. All these offensive and poisonous com- 
pounds of hydrogen concur in giving fetor and 
imparting to animal exhalations a poisonous 
action distinct from carbonic acid, in the same 
manner that they create the stench and fermen- 
tation of dead flesh. Both kinds of exhalations, 
those from living bodies and those from dead 
flesh, are the bearers of putrid and pestilential 
disease; and a congregation of filthy human 
beings in a confined space, and deprived of suffi- 
cient air, is as certain to generate putrid fever, 
as the infection from putrid dead bodies. This 
is the cause of the gaol pestilence, and of the 
various typhus fevers prevalent in the densely- 
inhabited dwellings of the poor. 
It has been found that young persons in good 
health are sweeter and evolve generally a less 
amount of fetid animal exhalations than the 
middle-aged and the old. The cause of this is 
obvious: these exhalations in clean and healthy 
individuals proceed, in a considerable degree, 
from the excess of nourishment not required for 
the support of the system, and which is there- 
fore got rid of by the insensible perspiration of 
the skin. Young people are still growing, if not 
in height, at least in the various structures of 
the body, which is not in full maturity till about 
the age of forty years. A greater amount of 
nutriment is therefore required to supply in 
them the secretions of formation. After the age 
of forty, there are no secretions of formation, 
but only of continuance ; therefore less chyle is 
required for the purposes of the animal frame. 
Yet not only is the same quantity of food taken, 
but often a great deal more. At the maturity 
of life, and as the body descends the vale of 
years, people indulge more in alimentiveness; 
hence an increase of fetid animal exhalations; 
hence, also, acid digestion and its attendants,— 
gout, gravel, and a variety of other diseases. 
That which the system cannot use, it must get 
rid of; and where, from excess in quantity, the 
573 
process of getting rid of it is impeded, disturb- 
ance must ensue. From this it may be inferred, 
that the space occupied by young people is, in 
general, somewhat less impregnated with animal 
effluvia, than that containing the middle-aged 
and the advanced in life. 
But in addition to the fetid exhalations of 
healthy persons, there are the still more perni- 
cious exhalations of bodies actually diseased, and 
of many others which, if not in a state of posi- 
tive disease, are at least in an unhealthy condi- 
tion, from excess of pleasure, intemperance in 
food and drinking, injudicious mercurial treat- 
ment, bad habits, or constitutional scrofula in 
some form or other. Thus, in crowded assem- 
blies, besides the carbonic acid generated, and 
the exhalations of the healthy portion of the 
company, the impurity of the air is further in- 
creased by the offensive emanations from tuber- 
culated lungs, foul ulcers, and loathsome dis- 
eases,—by the fumes of half-digested wine, spi- 
rits, ale, and porter,—by the odour of smoked 
cigars and the meerschaum,—the whole forming 
a tainted and disgusting compound breathed 
over and over again by all present. Is it, then, 
surprising, after dancing to excess in such an 
atmosphere, after remaining in and breathing it 
during a considerable number of hours, the mus- 
cles fatigued by exertion, the pores of the skin 
opened and relaxed, every organ of the body 
affected by the foul air and the unnatural heat, 
that a delicate girl should be injured by a sud- 
den and violent change of temperature, and from 
the bracing effect of the fresh air of which she 
had been so long deprived, should imbibe the 
germs of a disease that proves so fatal to the 
young and lovely? Hven the most robust are 
affected by such causes, which no human being 
can encounter with impunity, but which, on de- 
licate constitutions, are sure to plant the stan- 
dard of dissolution. 
The necessity of ventilation is, therefore, ma- 
nifest. Air fresh from household contamination 
ought to be freely admitted in sufficient quan- 
tity to carry off all animal exhalations. Carbonic 
acid, though heavier than air, being expanded 
by the heat of inhabited apartments, becomes 
lighter, flows out when its escape is possible, and 
gives place to a fresh and pure atmosphere. Such 
ventilation is indispensable not only in crowded 
rooms and assemblies, but in every apartment 
occupied by even a single individual. The same 
degree of ventilation found so useful in public 
hospitals for the cure of disease, is equally useful 
in private dwellings for its prevention. The ad- 
mission, into any room, of the pure atmosphere 
at a proper temperature never brings disease— 
quite the reverse; it often removes the cause of 
disease; and it is a striking fact that the ab- 
sence of the fresh pure air is the real cause of | 
those various indispositions that are imputed to 
its presence. Assuredly when the body is over- 
heated, and the vascular action of the skin ren- 
