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110°. It is not surprising that the vicinity of the steam
boat piers, near most of which large sewers empty their
contents, should be peculiarly offensive. The agitation
caused by the boats, and still more by the flood-tide,
stirs up this fermenting mud, rolls it a little way into
the stream, where it is kept always in a highly-concentrated
state, slowly moving in the back waters and
sluggish currents and shallows, which mostly exist inshore,
even in rapid rivers. Thus the concentrated sewage
and the hot mud on the banks and fore-shores maintain
a constant source of empoisonment, which has frequently
extended its influence into the mid-stream.
During the whole of last year, the water always
exhibited living animal and vegetable organisms. By
frequent experiments I found that if the water was kept
so as to putrify,—which it rarely would do at the ordinary
temperature of the air,—these organisms were
destroyed. In like manner by adding, hydrosulphuric
acid, ammonia, or acetic acid, products of putrefaction,
they Avere immediately killed. And during last June,
the black putrefying water contained no microscopic
plants or animals. The presence of these living organisms
is thus a proof of the salubrious condition of the
water.
Last year I never detected sulphuretted hydrogen
in the floAving Avater. In June this gas was occasionally
manifest. And Dr. Letheby has shown that the reason