Page:A Practical Treatise on Brewing (4th ed.).djvu/24

8 possible to suppose that any slight difference discoverable by analysis, in the quantities of carbonates or sulphates which may be dissolved in the water, could possibly affect either the flavour or quality of the beer.

Water, as usually met with, contains the following substances, which may, chemically speaking, be called impurities; namely,

Carbonic acid gas, to which the sparkling appearance of pump or spring water is owing.

Carbonate of lime, which is nearly insoluble in water, but which is often held in solution by excess of carbonic acid. When such water is boiled, the carbonic acid in excess is expelled, and the lime falls down, forming the crust in boilers and other similar vessels.

Sulphate of lime: this salt communicates the “hard” property, as it is called, to water, and is always known to be present, when soap which is dissolved in it curdles.

Besides these impurities, water always contains muriate of soda (common salt), and often other muriates. By using the term impurities, we do not intend to imply that anything exists in the Water, which, when it is drunk, renders it prejudicial: the term simply signifies any substance foreign to the real composition of water. Even rain-water, which is the result of a natural distillation, contains impurities.