Page:Popular Science Monthly Volume 32.djvu/883

Rh. Of the uses of potassium chloride but little is known. Sodium chloride, however, or common salt, has been more closely studied. In such proportions as the healthy taste demands, it is undoubtedly a valuable stimulant to the nutritive processes. The extent of the need for lime-salts in young animals is surprising. Iron is undoubtedly a food; for the quantity in the system is restored as fast as it is eliminated. Contrary to popular belief, the major portion of the iron of the human body is found, not in the blood but in the muscles, even after their contained blood has been removed. Silicic acid is found in very small quantities in bones, hair, and blood. It is supplied by many vegetable foods. Calcium fluoride is found in teeth, and to a slight extent in bone. Fortunately for us, these inorganic foods, whose withdrawal exercises deleterious influences on the economy, are, as a rule, present in great quantity in the actual foods in a mixed diet. In certain methods of preparing foods, however, their proportion is much diminished; thus, in the boiling of meats and vegetables, a large quantity of these important foodstuffs is extracted. Indeed, one of the chief dietetic advantages of salads and uncooked vegetables in general is, that these elements have not been removed.

Why do our Teeth decay so fast?—To this question Dr. Julius Pohlman answers, because we do not use them enough—showing that as a rule "those people who are least acquainted with the so-called hygiene of the teeth are the happy possessors of the soundest dentition"—like the negroes who chew sugar-cane, the German peasants, who are famous for their brilliant "Schwartz-brot-Zähne," or "rye-meal-bread teeth," polished but not worn out by daily mastication of dry, hard, black loaves, and the few old people left among us who persist in eating bread-crusts. Our weak and effeminate teeth are not used to hard work, and, like other organs that are not exercised, tend to atrophy. "The foundation for bad teeth," says this author, "is generally laid in early childhood; for numberless mothers and nurses very carefully soften the food or remove the crust from the bread before giving it to the little folks, because it may otherwise 'hurt their teeth,' and so the child grows up with a set of unused organs in its mouth; and when we have finally succeeded by the creation of artificial conditions in producing weak organs, then we wonder why the poor child has such bad teeth, and why it is so often suffering with toothache, and why the dentist's bill is so high. Teeth are organs specialized to perform the work of mastication; they are subject to the same laws that govern other organs, and their strength is determined by their use. Understanding this, we are obliged to admit that, if we ever become a toothless race, it will be our own fault."

Antiseptic Properties of Coffee.—The stimulating effects of the infusion of coffee have been referred to its excitant and tonic properties. Recent researches indicate that it has still more valuable qualities—those of an antiseptic. In 1885 M. Oppler announced the property which it possesses of preventing, to a certain extent, the development of micro-organisms in substances liable to putrefy. Then M. Sucksdorff showed that infusions of coffee and of tea might remain exposed openly to the air for a considerable time without molding or developing bacteria. Finally, Mr. Heim has recently published the results of more exact researches, which tend to demonstrate the reality of the antiseptic properties of roasted coffee. The cholera bacillus appears to be one of the organisms most readily affected by coffee. It is desirable to have the investigation extended to the infusion of tea, which will probably be found to have similar properties.

 A Crystal Skull.—Among the interesting features at the meeting of the American Association was the exhibition, by Mr. George F. Kunz, of a crystal skull which had been brought from Mexico by a Spanish officer before the French invasion, and, having been in possession of Mr. Evans, the English collector, and Mr. M. E. Boban, now belonged to Mr. George H. Sisson, of New York. The inclusions in the rock-crystal material were identical with those in the quartz or rock-crystal from Calaveras County, California. Nothing more than this is known of the origin of the skull. It is