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proportions have not been considerable during the
year, although in all cases the water has contained
more saline matter in winter during wet weather
than in summer—the maximum being in January
and February, and the minimum in September.
The hardness of the general supply has ranged, in
the case of the river water, from 14.8 to 15 degrees
of Clark's scale, and this has been reduced to about
4 degrees by boiling for a quarter of an hour. In
the case of the chalk-well water, the hardness has
been 20.7 degrees, and after boiling it has fallen to
5.7 degrees. The proportion of organic matter in
the water has been very small, for the quantity of
oxygen required to act on every description of oxydizable
matter has ranged from only 0.01 of a grain
per gallon in the chalk water of the Kent Company,
to 0.102 of a grain in the Thames water supplied by
the Grand Junction Company; and the amounts of
ammonia and of organic nitrogen, as determined by
Wanklyn's process, have not exceeded the 100th
part of a grain per gallon of water.
As regards turbidity, the water supplied to the
City by the New River and the East London Companies
has been invariably bright and nearly colourless,
and so also has been that of the Kent and the
West-Middlesex Companies, but that of the Southwark
and Vauxhall Company has been turbid on