"T HE water that we use every day is hardly ever pure. However clear it may be, it always contains certain foreign substances in solution, as is proved by the slight coating of earthy matter that forms little by little on the inside of our water-bottles, tarnishing the glass and lessening its transparency."
"That earthy coating is very hard to wash off," remarked Marie. "I remember one day I tried and tried to get it off with water alone, but it seemed to have become a part of the glass itself."
"Yes, that coating sticks so fast just because it is of stony matter, of veritable stone such as the mason uses for building our houses. It is not at all surprising, therefore, if mere washing with water fails to remove it. To make it let go its hold it should be dissolved in an acid, vinegar for example, or lemon-juice. Pour a little vinegar into a carafe and shake it up until it has wet all the clouded part of the glass; you will see the stony coating dissolve, creating a little foam as it does so. When the acid has done its work, wash it off with water, and you will find that all the foreign matter comes away with it, leaving the glass once more as clear and transparent as ever."
"Then even the clearest water," Jules observed, "water in which the eye can detect nothing, absolutely nothing, nevertheless contains dissolved stone, just as sweetened water contains sugar invisible to the eye; and when we drink a glass of water we drink with it a little of this stony matter. Who would ever suspect it!"
"It is very fortunate, my dear boy, that we do thus drink a little of this dissolved stone. Our bodies, in order to grow and become strong, require a certain proportion of stony matter for the formation of our bones, which are to us what its solid framework is to a house. This needed matter we cannot by any possibility create by ourselves; we must get it from our food and drink. Water, for its part, furnishes a good share, and if it did not contain the required mineral matter we should remain puny and ailing, being unable to attain our natural size."
"Is there much of this dissolved stone in the water we drink?' asked Emile.
"To be fit for drinking, water must contain a little, for the reason I have just explained; but when it contains too much it is hard to digest and burdens the stomach. The right proportion is from one to two decigrams for a liter of water; or, in other words, about as much as you would take up between your thumb and forefinger. Any considerable excess makes the water heavy, as we say, because it weighs on the stomach.
"Certain waters are so rich in dissolved stony matter that they quickly encrust anything they touch. Such is the water of the celebrated spring of Saint Allyre at Clermont-Ferrand. It is made to fall upon a heap of tree branches which break up the water and divide it into spray. This fine shower is allowed to fall on objects that it is desired to coat with an incrustation of stone—on birds' nests, baskets of fruit, bouquets of flowers, and foliage. A layer of stony matter is soon deposited by this mineralized dew, and the birds' nest, the basket of fruit, the bouquet are turned to stone, or, more exactly they are overlaid with a coating of stone, so that one would say a sculptor's chisel had deftly cut these objects out of marble. Such water, needless to say, is unfit for drinking."
"I should think so!" cried Claire. "It would pave the stomach with marble, which would not be very good for the digestion."
"Never does the water such as we use," Uncle Paul continued, "have anything like that super-abundance of stony matter, though it often does contain enough to cause difficulty in certain domestic operations, especially laundry-work. You must have noticed how the water in which clothes are washed with soap always turns more or less white; perhaps you have even observed that little flakes or clots of whitish matter are formed in the water and float about in it."
"Yes, I know what you mean," Marie hastened to reply; "and when there are too many of those white clots it is hard to get any suds; the soap is just wasted."
"Well, now you will know that the white tinge and the floating particles are caused by the presence of dissolved stony substances. Perfectly pure water, distilled water, takes up soap without losing its clearness, or with very little loss; it does not turn white, it does not form flakes. To convince yourselves of this, try a little rain-water some day for washing out a piece of linen; for rain-water is almost as pure as distilled water. You will see how easy it is and how the soap does its work without waste. There will be no white particles left in the water, though there will be plenty of lather, and no whitish tinge to the water under the foam such as you commonly see in wash-tubs.
"When water turns very white under the action of soap and shows abundant flakes, it is a sure sign of too much stony matter in the water. Laundry-work then becomes difficult and soap gives trouble about dissolving, dissipating itself in tiny clots without acting on the soiled linen. Such water is also bad for drinking, overburdening the stomach with its excess of mineral matter. The water found in regions rich in limestone is liable to this objection."
"I can see well enough," said Emile, "that a little stony substance in the water must be a good thing for us, and I also see how troublesome too much must be. The stomach would soon get tired of digesting stone."
"Finally," his uncle continued, "hard water like that is unfit for certain culinary purposes, particularly cooking vegetables such as green peas, and chick-peas—the last named especially. The mineral matter in the water becomes incorporated with the vegetables and then, no matter how long you boil them, they will not become soft."
"Yes," said Marie, "I know how chick-peas act sometimes; after hours and hours of cooking they are just as hard as at first and will bound like marbles if you throw them on the floor. What prevents their softening, you say, is the stony matter dissolved in the water."
"That, and nothing else. Now, since all water contains more or less of this, we are often troubled about cooking the vegetables I have named. But there is a simple remedy that I recommend in all such cases: drop a little pinch of potash into the water, and the most obstinate beans or peas will cook to perfection, even the chick-pea itself softening to a mush."
"Without getting any bad taste?" asked Marie.
"Without getting any bad taste or anything else that need be feared, on condition, however, that the potash be used very sparingly—just a pinch and no more.
"But there is another way to use it that is more readily at our command. Since potash is obtained from wood-ashes it is plain that wood-ashes can here play the part of potash. In a small piece of cotton cloth folded two or three times tie up a thimbleful of clean ashes, and drop this into the pot with your vegetables. The potash in the ashes will dissolve and permeate the water, while the earthy matter will be left in the cloth, which is to be taken out when the vegetables are done. By this means, however hard the water, you will get the better of the most refractory peas and beans."
"Uncle Paul is always finding some new use for wood-ashes," remarked Claire; "and now we see that they will soften even the hardest of chick-peas."