The Romance of Modern Chemistry

NATURAL WATERS had to give up when the water was boiled for ten minutes. As the palatable quality of a water depends on the quantity of dissolved gases, such as oxygen and carbon dioxide, the device of boiling it renders it some- what insipid. If this is considered a disadvantage, it can be made more palatable by aeration, that is, by shaking it for a little with air. Besides the various kinds of fresh water and the brackish water of our seas and inland lakes, Nature supplies us here and there with waters of a peculiar kind, distinguished not so much by the quantity of matter which they contain as by the fact that this matter is of an unusual kind. There are the so-called “mineral waters,* which, in many cases at least, come from considerable depths below the surface, and are frequently hot on that account. Some of the well-known mineral waters are alkaline and contain carbonate of soda, notably those which are charged with extra large quantities of carbon dioxide, such as Apollinaris and Seltzer waters. Carbon dioxide has been forced into these waters under high pressure far below ground, and when they come to the surface and under the lower pressure which prevails there they cannot contain them- selves, as it were, and so are marked by their characteristic effervescence. Here and there one finds iron or chalybeate springs. Carbonate of iron, like carbonate of lime, is not soluble in pure water, but is taken up by water charged with carbon dioxide. Thus it is possible to obtain a water which holds in solution a considerable quantity of other- wise insoluble iron. When such a water comes to the surface, it loses some of the carbon dioxide with which it is charged, and the channel down which the water runs 104