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Page:Popular Science Monthly Volume 3.djvu/263

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MISCELLANY.

but little for ornament. The ordinary service of a set of teeth is about five years, but they frequently last much longer. All full upper sets are retained by atmospheric pressure. This principle is coeval with the art. In Japan, dentistry exists only as a mechanical trade, and the status of those who practice it is not very high. It is, in fact, graded with the carpenters—their word hadyikfsan meaning tooth-carpenter.

 

Vegetable Ivory.—The kernel of the corrozzo-nut so closely resembles ivory as to merit the title of vegetable ivory. The plant (Phytclephas macrocarpa) which produces this nut belongs to the palm-tribe. It grows in South America, and possesses extraordinary beauty. The stem is short, and lies along the ground, but from its crown issues a sheaf of light-green, pinnated leaves, like ostrich-plumes, which often attain a height of 30 or 40 feet. The fruit of the plant is as large as a man's head, and contains a number of nuts of rough, triangular shape, each being almost as large as a hen's egg. When fully ripe, the kernel of the nut is very hard and white, and hence the name phytelephas (vegetable ivory). This is now largely used as a substitute for elephant ivory, in the manufacture of buttons and various ornaments, and might easily pass for the animal product. Indeed, the best judges are often deceived by the close resemblance between the two. Advantage is taken of this circumstance in Germany by dealers in bone-dust to adulterate their wares with the waste of the factories where the vegetable ivory is manufactured. The best mode of detecting the adulteration is to burn the suspected article. If it contains any considerable amount of the vegetable substance, the application of heat will cause it to give out an odor much like that of roasting coffee; but, if it is pure bone-dust, or nearly so, it will emit a nauseous and very disagreeable stench.

 

Coloring Matter in Blood.—A writer in Virchow's Archiv finds in blood two distinct coloring-matters. One of these is readily soluble in water and alcohol, but not so readily in ether. When dry it has a dark, greenish-brown color, and is carbonized on the application of heat, without ebullition. The ash is strongly colored with iron, and contains phosphoric and silicic acids, and a trace of alkali. It does not yield hemin-crystals under any treatment. With guaiacum-tincture and turpentine-oil it gives the well-known blue color, and under the spectroscope is found to possess the characters attributed to alkaline oxyhematin by Preyer. It appears to be identical with Von Wittich's hematin. The other coloring-matter consists of dark, blue-black microscopic crystals, insoluble in water, alcohol, ether, chloroform, and acids, but soluble in weak alkaline solutions, to which they give a brownish tint. If it be then precipitated by acetic acid, and dried, it will, on being treated with sal-ammoniac and glacial acetic acid, yield beautiful hemin-crystals. When reduced to an ash, it consists of pure oxide of iron. It seems to be identical with Virchow's hematoidin.

 

Elimination of Carbonic Acid by the Skin.—The amount of carbonic acid given out of the system through the skin in man has been variously estimated by physiologists; but, as their methods of determination were all more or less defective, it is not surprising that their results should differ very considerably from one another. Thus Reinhard's estimate makes the average daily elimination of carbonic acid through the skin about 35 grains, while Gerlach makes it 120 grains; other authorities ranging all along between these two extremes. A special apparatus has been devised by Dr. Aubert, of Rostock, for more accurately ascertaining the amount of this excretion. He seats a person within a box, which fits lightly around the neck, and through which a gentle current of air is passed. Dr. Aubert, in this way, finds that in the course of 24 hours a maximum of 97 and a minimum of 35½ grains of carbonic acid are eliminated by the skin of the whole body, exclusive of the head. Variations of temperature will of course affect the amount of carbonic acid thus excreted. In the experiment, the external temperature was about 86° Fahr.

 

Remarkable Diamonds.—A diamond waa recently discovered, at the Cape of Good Hope, which weighs 288 carats. This the