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on tlie oilier, some of tiie less diffusible atmospheric contaminations, such as 
ordinary bodily exhalations, wliich are not commonly perceptible to the nose, 
can be distinguished by persons of more than common acuteness of smell, 
especially when proceeding from the bodies of the sick. The effluvia which 
certain wild animals leave on their tracks, and which constitute the ‘scent’ 
of the hunting-field, afford a familiar example of the latter substances. In 
the parliamentary report which he drew up, in 1847i on the subject of dis¬ 
infectants, Dr. Leeson succeeded in showing very clearly that there is no 
necessary relation between the odorous and deleterious properties of atmo- 
speric impurities, and that merely to deodorize is not necessarily to disinfect. 
^With reference to this point, he classifies the elements of morbid animal 
exhalations and malarious and putrefactive vapours as follows : 
Dangerous, but 
inodorous. 
Remittent miasms 
Typhoid miasms 
Carbonic oxide 
Carbonic acid 
Odorous but slighllg 
offensive. 
Ammonia 
Curb, ammon. 
Cyanogen 
Sulpho-cyanogen 
Most offensive, but not 
infectious. 
Sulphuretted hydrogen 
Phosph. hydrogen 
Carburetted hydrogen 
Sulph. ammon. 
Having referred to the researches of Ehreiiberg on infu¬ 
sorial organisms, Mr. Condy adverts to more diffusible 
contaminations, emanations of effete matter, which are con¬ 
stantly proceeding from organized beings and their excreta, 
especially during disease, as well as to the organic matter 
existing in human and other exhalations. According to 
Dr. R. Angus Smith, respired air contains 3 per 1000 of 
animal matter in the form of putrescible albuminoid sub¬ 
stances. Dr. Eiselt, of Prague, has discovered pus-cells in 
the air of the Or[)han Asylum of that city. Now, it is 
with impurities of this nature, and others allied to them, 
that contagion and infection are intimately connected, and 
hence the desirability of possessing means to effect their 
destruction. 
“The atmosphere is therefore evidently subject to very considerable 
variations in respect to the substances which it contains; in some places, 
and under certain circumstances, it is much more pure than in others. The 
two extremes are probably to be found, on the one hand, at or near the 
ocean, which has the effect of absorbing any heterogeneous particles present, 
and on the other in crowded localities in large towns, more especially in 
hospitals and places containing large numbers of sick. The air in both of 
these extremes of purity and impurity, as well as in all the innumerable 
intermediate conditions, is capable of supporting life, at least for a limited 
period. It may usually bo considered sufficiently pure for the purposes of 
respiration and animal health, when its chemical properl ies are those of 
oxygen—that great mainspring of all organic activities. With few excep¬ 
tions, this is the case with the‘open air,’apart from artificial shelters 
where men or domestic animals are more or less closely congregated 
together. Tiie effects ))roduced on the system by a foul atmosphere 
depend in a considerable degree on the state of body and the coustjlutiou 
and habits of those exi)osed to its influence; for the air of even the worst 
veiiLiiated places is hardly ever so impure as to be rapidly destructive to tiie 
