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180
The solid matters in the water are almost wholly
composed of mineral substances, which, in the proportion
in which they exist in Metropolitan waters, in
no way diminish the fitness of the water for drinking.
But the salts of lime and magnesia which
constitute the principal part of these mineral
ingredients are objectionable, not only because they
impart to the water what is known as "hardness,"
and thus render it unsuitable for washing, but also
because they cause incrustations and deposits in steam
and kitchen boilers and hot-water pipes.
The saline matters dissolved in the deep-well water
from the chalk are considerably greater in amount than
those found in the river water, and inasmuch as this
chalk-water is sent out in its natural condition by
the Kent and East London Companies and by the
Tottenham Local Board of Health, these supplies
contained in two out of three cases, more solid matter
than any of the others. The Colne Valley Company,
on the other hand, by treating this chalk-water with
lime before delivery, so reduced the solid matter that
the latter was one-third less than the amount present
in the river waters, and was about one-half of that in
the deep-well waters either of the Kent Company or
of the Tottenham Local Board of Health.
The comparatively small proportion of organic
material which the solid matter invariably contains is,
on the other hand, of great importance in connexion
with the use of the water for drinking purposes. For