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322 FRAGMEN TS OF SCIENCE.

quainted with the works. At Canterbury there are three
reservoirs covered in and protected by a concrete roof and
layers of pebbles both from the summer’s heat and the win-
ter’s cold. Each reservoir contains 120,000 gallons of chalk-
water. Adjacent to these reservoirs are others containing
pure slaCked lime—the so—called “cream of lime.” These
are filled with water, the lime and water being thoroughly
mixed by air forced in by an engine through apertures in
the bottom of the reservoir. The water thus well mixed
with the lime soon dissolves all of this substance that it is
capable of dissolving. The lime is then allowed to subside
to the bottom, leaving a perfectly clear lime-water behind.
The object is now to soften the chalk-water. Into the
empty reservoir is introduced a certain quantity of the clear
lime-water, and after this about nine times the quantity of the
chalk-water. The transparency immediately disappears—
the mixture of the two clear liquids becomes thickly turbid.
The carbonate Of lime is precipitated, and the precipitate is
permitted to subside ; it is crystalline and heavy, and there-
fore sinks rapidly. In about twelve hours you find a layer
of pure white carbonate of lime at the bottom of the reservoir,
with a Water of extraordinary beauty and purity overhead.
A few days ago I pitched some halfpence into a reservoir
sixteen feet deep at the Chilton Hills. The sixteen feet
hardly perceptibly dimmed the coin. Had I cast a pin in,
it could, I am persuaded, have been seen at the bottom. By
this process of softening the water is reduced from about
seventeen degrees of hardness to three degrees of hardness.
It yields a lather immediately. Its temperature is constant
throughout the year. In the hOttest summer it is cool, its
temperature being 20° above the freezing-point; and it
does not freeze in winter if conveyed in proper pipes. It
is not exposed to the contamination of either earth or air.
The reservoirs are covered; a leaf cannot blow into the
water, no surface contamination can reach it, it passes di-

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