obably not over one fiftieth part of the
water is so neutralized, so that the added cost of soap is actually
about $2.80 a day. Whipple expresses this cost as _H_/100 = _D_, where H
is the hardness in parts per million and _D_ is the cost in cents for
every 1000 gallons used for all purposes. Thus Canisteo water costs
162.8/100 = 1.6 cents per 1000 gallons used, while Catskill costs only
22.1/100 or 0.2 cent on account of soap.

This discussion is intended to suggest a comparison between a well of
hard water and a surface supply of soft water, when both are available.
It should arouse an interest in securing a soft water as well as a clear
water, and the advantages of the softer water, in so far as soap
consumption alone is concerned, are seen to be not inconsiderable.

_Vegetable pollution._

The vegetable and animal matter is organic in its origin and nature, and
their effect on water may be taken up together.

Vegetable pollution is generally the result of decayed leaves, roots,
bark, and such other vegetable tissue as would be likely to be found
where the water-supply flows through a swamp or accumulates in hollows
and depressions. This sort of water is likely to have a brownish or
yellowish brown color, to have a slightly sweetish taste, and to be
soft, that is, free from mineral solids. Usually such water can be used
for drinking purposes without serious consequences. AEsthetically, it is
objectionable because of its color, and the city of Boston has expended
many thousands dollars in building channels around swamps and in
providing artificial outlets for swamps, so that the color of the water
collected on the watershed shall not show the color induced thereby.
Water from the Dismal Swamp of Virginia is so discolored as to look like
coffee, and yet, in the vicinity, it is much prized for drinking, and
formerly great pains were taken to fill casks with this water when in
preparation for a long sea voyage.

Such matter always has a marked influence on a chemical analysis of the
water, shows large amounts of nitrogenous matter, and apparently
indicates a polluted supply; but, if the reason for this apparent
pollution lies in the presence of a swamp, no danger to health therefrom
is to be apprehended. Such water also is less subject to decay or
putrefaction, and if a water-supply for a house is to be taken from a
small pond, a gathering ground containing swamps is likely to furnish a
more satisfactory water, colo