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168
all the industrial uses of water. Thus in the washing of linen the
economy effected by the use of soft water is very great indeed, for since
it is indispensable to have soft water for this purpose, if the water
employed is initially hard it must be softened, either by means of
carbonate of soda or by the expenditure of a larger quantity of soap.
By far the most economical method of softening water is by means of
lime (Clark's process) which can be carried out on the largest scale, at a
cost of about one-eightieth part of that which the use of extra soap
entails on the consumer. The only water which is well fitted for
washing and industrial purposes generally, is that of the Colne Valley
Company, which in its natural state is hard like that of the Kent
Company, but which by treatment with lime has its hardness reduced
before delivery to less than one-sixth of its original amount. The
hardness of the river supplies is also capable of similar reduction.
A small proportion of the solid matter in water is always organic in nature,
and this, although quite insignificant as regards its absolute amount, is
yet of the greatest importance when its possible origin is taken into
consideration. The rivers receive above the intakes of the Companies
a certain amount of animal matter, derived partly from sewers, cesspools,
and sewage works, and partly from manured land. Such animal
substances may at any time be accompanied by matters capable of producing
zymotic disease ; and, although the treatment which the water subsequently
receives at the hands of the Companies is calculated greatly to
diminish the risk of such morbific matter reaching the consumer, its
entire removal is not guaranteed. It is, therefore, satisfactory to know
that most of the Companies are making serious efforts to diminish
the volume of water taken directly from the streams. It is desirable,
however, that this action of the water Companies should be supplemented
by the enforcement of the laws prohibiting the discharge of
sewage into the Thames and Lea."
"The amount of organic matter was very moderate during the
months of March, May, June, July, August, September, October, and
November, whilst during the remaining four months, and especially in
December, the proportion was considerably greater. The
average proportion of organic matter present in the deep well water,
almost uniformly small in quantity throughout the year, was less
than one-third as great as that found in the Thames, and less than
half of that present in the water of the Lea. The real
superiority of the deep well water, moreover, is not fully indicated by
these figures, for the process of filtration to which the deep well water
has been subjected in traversing the porous strata from which it has
been derived, is far more exhaustive than can be effected by the sand
filtration to which the river waters are submitted."