The cost of softening 1,000 gallons of water is :-

One halfpenny for every 10 degrees of temporary hardness present.

Three-halfpence for every 10 degrees of permanent hardness present.

Each 100,000 gallons of hard water evaporated will deposit in the boiler :-

1431bs. of scale-forming matter for every 10 degrees of hardness.

215lbs. of scale-forming matter for every 15 degrees of hardness.

3581bs. of scale-forming matter for every 25 degrees of hardness.

Scale in a boiler causes (a) a great waste of fuel, (b) an enormous unnecessary strain on the boiler.

The coal wasted varies with the depth of scale and the design of the boiler, but with water of average hardness is seldom less than 10 per cent.

Taking coal at 20/- per ton, this means an increase of nearly 101/2d. per 1,000 gallons in the cost of evaporation, a heavy price to pay for hard water.

To the amount lost on wasted coal must be added the wages paid for periodical chipping and cleaning, and the bill for boiler compounds and so-called scale-looseners, chemical or mechanical.

The extra strain on a boiler may be gauged from the fact that, whereas the temperature of a clean boiler plate is 350 degrees Fahr., the temperature of the same plate covered with 1/2in. of scale is 750 degrees, i.e., the scale-covered plate has to be heated 400 degrees above the temperature required to convert the water into steam.

This is often a source of serious loss and sometimes of danger.

A 1/2in. furnace plate covered with 10 in. scale is as efficient a heat re-tarder as a steel furnace plate 101/2in. thick.