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sodium—the latter amounting to 2.62 grains per
gallon of the chalk water, and to about 1¾ per
gallon of the Thames and New River sources. The
amount of organic matter has at all times been insignificant,
for the quantity of oxygen required by
every kind of oxydisable matter has not exceeded the
0'079 of a grain per gallon of water—the range has
been from 0.007 of a grain for the chalk water to
0.079 of a grain for the worst description of Thames
water. The nitrogen, as organic and saline ammonia,
has also been remarkably small in quantity, amounting
to only a trace in the Kent Company's water, and to
less than the one-hundredth part of a grain in a gallon
of Thames or New River water. The hardness of
the water was generally about 15 degrees, and this
was reduced to about 3½ degrees by boiling the water
for a quarter of an hour. In the case of the Kent
water from the chalk wells, the hardness was 21 degrees
before boiling, and 5*8 degrees after.
As regards turbidity, it was noticed that the water
supplied by the West Middlesex, the New River, the
East London, and the Kent Companies, was always
bright and nearly colourless when examined in large
volume, as in a glass tube two feet in length, but that
of the other companies was at times slightly turbid
from the presence of finely divided clay of a perfectly
harmless character.
The quantity of water daily supplied to the Metropolis
by the several companies has ranged from 101