We need for carrying out these manipulations, according to the size
of the establishment, one or more reservoirs for precipitating the
impurities of the water, and one pure water reservoir, to take up the
purified water; from the latter reservoir the boilers are fed. The most
practical idea would be to arrange the precipitating reservoir in such
manner that the purified water can flow directly into the feeding
reservoir.
The water in the precipitating reservoir is heated either by adding
boiling water or letting in steam up to 60° C. at least. The
precipitating reservoirs (square iron vessels or horizontal
cylinders--old boilers) of no more than 4 or 4½ feet, having a faucet 6
inches above the bottom, through which the purified water is drawn off,
and another one at the bottom of the vessel, to let the precipitate off
and allow of a perfect cleaning. In a factory with six or seven boilers
of the usual size, making together 400 square meters heating surface,
two precipitating reservoirs, of ten cubic meters each, and one pure
water reservoir of ten or fifteen cubic meter capacity, are used.
In twenty-four hours about 240 cubic meters of water are evaporated; we
have, therefore, to purify twenty-four precipitating reservoirs at ten
cubic meters each day, or ten cubic meters each hour.
It is profitable to surround the reservoirs with inferior conductors of
heat, to avoid losses.
The contents of the precipitating reservoirs have to be stirred up very
well, and for this purpose we can either arrange a mechanical stirrer
or do it by hand, or the best would be a "Korting steam stirring and
blowing apparatus." In using the latter we only have to open the valve,
whereby in a very short time the air driven through the water stirs this
up and mixes it thoroughly with the precipitating ingredients. In a
factory where boilers of only 15 to 100 square meters heating surface
are, one precipitating reservoir of two to ten cubic meters and one pure
water reservoir of three to ten cubic meters capacity are required. For
locomobiles, two wooden tubs or barrels are sufficient.