Among the best samples of boiler compounds ever sent to the laboratory for analysis were those found to be composed of:
| Sal-soda | 40 | Pounds |
| Catichu | 5 | „ |
| Sal-ammoniac | 5 | „ |
This solution was formerly sold at a good round figure, but since its nature became more generally known, it is not found in the market, but it is largely used, consumers putting it up in lots sufficient to last a year or so at a time.
The above is strongly recommended by those who have used it, one pound of the mixture being added to each barrel of water used, but after the scale is once thoroughly removed from the boiler, the use of sal-soda is all that is necessary.
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There are other evils sometimes inherent in hard waters above the mere production of a crust. Some waters contain a great deal of soluble magnesia salts, together with common salt. When this is the case there is a great probability of corrosion, for the former is attacked by steam at high pressure in such a way that muriatic acid fumes are produced, which seriously corrode the boiler, and what is far worse, passes with the steam into the engine, and sets up corrosion in the cylinders and other delicate fittings with which the steam comes in contact. All this can, however, be obviated by the removal of the magnesia from the water.
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When water attains a high temperature, as it does under increasing pressure, ranging from 175° to about 420° Fahr., all carbonates, sulphates and chlorides are deposited in the following order:
First. Carbonate of lime at 176° and 248° Fahr.
Second. Sulphate of lime at 248° and 420°.