572 
electric, is, nevertheless, one of the elements in 
all compounds generating putrid disease. The 
sulphuretted hydrogen is a union of hydrogen 
gas with sulphur, forming an invisible gas hea- 
vier than common air in the proportion of 36'764 
to 30°8115, and so dreadfully poisonous that one 
part of it, mixed with 249 parts of air, would 
destroy a horse if breathed by that animal. Pro- 
fessor Donovan states that a greenfinch died 
instantly in air containing one fifteen hundredth 
part of its volume of this gas; and that if the 
body of a rabbit be enveloped in it, though the 
head of the animal be exposed to the pure air, it 
will die in a quarter of an hour. Some indivi- 
duals give out so large a quantity of this gas, 
as to discolour white paint. Its odour, when 
isolated, is that of rotten eggs, it being precisely 
to the emission of sulphuretted hydrogen that 
these owe their odious stench. Hydrogen and 
phosphorus form several combinations equally 
offensive. The phosphuretted hydrogen is a 
transparent colourless gas, having, when free, an 
odour resembling that of putrid fish. Ammonia 
is largely generated in all animal bodies, and 
plays a most important part in the dangerous 
action of animal exhalations upon the human 
frame. The constituents of it are hydrogen and 
nitrogen; and the latter of these is the imme- 
diate agent of all decomposing action upon or- 
ganised matter, from the vinous fermentation 
which, by the decomposition of sugar produces 
alcohol and vinegar, to the decomposition of 
dead animal structures by putrefaction. In all 
these cases the process is the same,—and so is 
the ultimate result; the action leading, through 
various changes, to complete dissolution and dis- 
persion of the elements, which enter into new 
combinations. The nitrogen, in its efforts to 
liberate itself, having first acted upon the gluten 
contained in the mucilage of sugar or grape 
juice, or in malt,—this, in the form of yeast, 
continues its action upon the sugar, which is 
converted into wine, afterwards into vinegar, 
and ultimately into an unwholesome putrid li- 
quor free from either alcohol or vinegar. In 
like manner, the nitrogen acts as a ferment to 
dead animal matter, which once in a state of 
putrefaction communicates its condition not only 
to any other dead animal matter in contact with 
it, but to living beings within its influence, pro- 
ducing those dreadful fevers and putrid sores 
which, in all our large towns, sweep away so 
many human beings every year; and in some 
other countries generating that horrible disease 
called the plague, from which the habits of supe- 
rior civilisation have freed our island, but to 
which we were formerly subject from the ex- 
tremely unclean state of our houses and our per- 
sons. ‘The exhalations, then, from human beings, 
are deadly poisons to human beings, and, in 
the case of the four individuals shut up in a 
close room, as we have supposed further up, 
would engender typhus fever, even if there were 
a 
VENTILATION. 
nothing to dread from the deadly effects of the 
carbonic acid and the absence of oxygen. All 
this shows the necessity of perfect ventilation in 
our dwelling-houses and public establishments. 
When a small close room is occupied for an 
hour or two by even a single individual, and one 
too of the most cleanly habits, of the most deli- 
cate and fragrant person, any one entering it 
from the external air will perceive a faint, fetid 
odour, which certainly does not proceed from the 
odourless carbonic acid, or the odourless nitro- 
gen; and when several individuals are assembled 
in such an apartment, the fetid smell is strong 
and particularly offensive, though they them- 
selves may become insensible to the nuisance. 
Pastilles are burnt, or perfumes used, to ‘ purify 
the air of the room,’ as it is alleged; but such 
expedients only increase the danger ; because the 
pastilles are made of charcoal, sandal-wood, and 
other perfumes; and the burning of these pro- 
duces no other effect than to diminish the quan- 
tity of oxygen, and increase that of carbonic 
acid. The atmosphere of a bedroom in which an 
adult human being has slept, will, in the morn- 
ing, be found impregnated with a fetid odour, 
which, from the idiosyncracy of some individu- 
als, is extremely offensive; and this odour is 
increased by the pernicious practice of not only 
closing the door and windows, but stopping up 
the chimney as well, so as to prevent the escape 
of the offensive gas, at the same time that the 
fresh air has no power of entering. A large body 
of assembled men and women, whether consist- 
ing of lords and courtly dames at a court draw- 
ing-room, or of a mixed congregation in a church, 
or of the unwashed multitude in a mob, emit the 
same offensive effluvia, despite of musk, or am- 
bergris, or that most exquisite perfume Ede’s 
hedyosmia, each of which, like every other toi- 
lette perfume, carries in its sweets the poisonous 
carbon. The stench given out by human beings 
is an agent of death independent of carbonic 
acid, and one of more fatal import, too, because 
charged with the germs of infection. It is, in 
fact, a true putrid ferment, bringing to matter, 
still possessed of the vital power, the principle 
of ultimate decomposition. This principle, the 
cause of the fetor emitted, is a most malignant 
and destructive poison when reabsorbed by the 
system ; it is nothing less, though in a modified 
form, than the principle given out by the putre- 
faction of dead animal matter. 
Besides the ultimate elements of animal mat- 
ter, oxygen, hydrogen, nitrogen, and carbon— 
elements belonging as much to the snail and the 
worm as to the flesh of man, or to that of the 
dog, the tiger, and the elephant, or any other 
breathing thing—sulphur, phosphorus, ammonia, 
potash, soda, lime, and many other chemical 
substances, exist in the human animal struc- 
tures. Many of these matters are taken into 
the body with the food, for the purposes of life ; 
and others are obtained by respiration, and by 
