The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1892-06-05
SELF PURlFlcATloN OF WATER.
1t Is of Some Advantage, but Not Enough
to Do without FiItering.

/
| to Do Without FiItering.
| Impure streams that flow through rich
| agricultural and densely populated re-
| gions are apparently purified by dilution
| from springs along the banks and the in
| flowing smaller streams of less impure
| water. The by-products of chemical fac
tories that are thrown into streams, and
which are neither removed by chemical
action nor Instrumentation, are frequently
SO diluted by few miles flow that the
water becomes harmless, although at the
factories it may be strong antiseptic.
Streams become purified TO the greatest
extent, however, by a process of sedimen
tation, which, in its origin, is largely in
fuenced by chemical action. This takes
place as the velocity Of the current dim
inishes, when much Of the insoluble mat.
ter subsidies, removing with it organic
matter that would remain in suspension OF
solution for many days Along slowly
running streams can be seen in summer
organic Accommodations on stones laid down
by sedimentation.
A careful study of the various natural
processes Of publication have led DR.. Percy
f. FARMLAND, OF England, to the conclu
sion that not only is sedimentation the
principal cause of the natural removal OF
decaying organic matter from river water
but that it is also the principal cause Of the
partial disappearance of germs. The lat
ter is of great hygienic Importance in both
natural and artificial publication of water
But nature does not completely remove
organic matter and heterogeneous from
river water. The distance required for
reasonable separation of the former in our
American streams is generally not more
than fifteen or twenty miles and often
much less. The Hudson river, which re.
ceives the sewage Of Troy, becomes reason.
ably free of its organic matter in the six OF
eight miles flow to the city of Albany.
But owing to the small size of some Eng.
lish streams, like the rivers Severn, Tees
and Wear, and the great population or
their banks, the waters remain unfit for
use many miles below the points of con.
tamination, and the royal commissioners
concluded that there is not a river in all
England sufficiently long to free itself
through natural agencies of even a moder-
ate amount of sewage.
The self publication of water in streams
is no guaranty that it is wholesome at any
distance below the place where it is GER
tainly contaminated with products of the
human body, for although the organic
matter and even the germs may be largely
removed it is unsafe to drink water fol
any length of time that contains even a
few infectious bacteria. When river wa.
ter has once been polluted with excrementi-
tious washings from diseased patients, it
should never be used directly or from city
water works without due consideration OF
its nature and the possibility of its pro
ducing disease.
Nature also purifies water to consid
cradle extent in freezing, and the product
deserves our attention, for there is a rapid
ly increasing demand for ice in the United
States, where we are already cutting some
100000 tons annually. Those who fire
quently examine ice and have followed
Tyndall, Cramer, Leone, Fraenkel, Engel
mann, Pengra, Prudden and others in
their Investigations know that water is
only partially purified in freezing The
freezing process removed for Pengra only
from 20 to so per cent. of the organic mat
ter, 40 per cent. of the inorganic salts, ano
about 80 per cent. of the micro-organisms.
The diminution of the bacteria in water
in freezing is owing largely to their de-
struction instead of expulsion But some
species of bacteria have great power OF
withstanding cold, and the bacillus of ty.
phoid fever has been found in ice several
months after its formation, and there are
many classes of germs that cannot be de
stroyed by freezing alone. When such i'm.
pure ice is melted the living germs regain
their activity, and if pathogenic are capa
BILE of producing disease. Impure snow wa
ter is also sometimes detrimental to health |
Engineering Magazine.