Page:Popular Science Monthly Volume 47.djvu/150

142 gas, by the simple action of water on calcium carbide has been mentioned in the Monthly. Great possibilities from the use of this method are foreshadowed by Prof. Vivian B. Lewes. The property possessed by calcic carbide of forming acetylene with water was accidentally discovered while working with the electric furnace to form an alloy of calcium. A mixture containing lime and powdered anthracite was fused down to a semi-metallic mass, which, proving not to be desired, was thrown into a bucket containing water, when a rapid effervescence took place, and the escaping gas burned, on the application of a light, with a smoky but luminous flame. This source of light can be produced by the exposure to the electric furnace of finely ground chalk or lime mixed with powdered carbon in any form. When the calcic carbide is placed in a glass flask and water is allowed slowly to drip upon it from a dropping tube, the decomposition begins at once with considerable rapidity, and the acetylene pours off in a continuous stream; as the decomposition continues, the solid mass in the flask swells up and is eventually converted into a mass of slacked lime. The value of this useful product may be deducted in computing the cost of the acetylene. For commercial purposes the carbide may be cast direct from the electric furnace into rods or cylindrical cartridges, which, when twelve inches long and an inch and a quarter in diameter, will weigh one pound and will give five cubic feet of gas. Acetylene is a clear, colorless gas, with an intensely penetrating odor which somewhat resembles garlic. The strong smell is a great safeguard in its use, and, when the quantity of the gas is dangerous, can not be endured. Hence, while poisonous like carbon monoxide, its use, on account of its odor, is much more safe. When burned it emits a light greater than that given by any known gas, its illuminating power, calculated to a consumption of five cubic feet an hour, being two hundred and forty candles. It being liquefiable with comparative ease, enormous volumes of it may be compressed in small wrought-iron or steel cylinders, in which it may be stored and from them burned as wanted. It should not be used with silver or copper, as it forms explosive compounds with their ammoniacal solutions. Advantage may be taken of the calcic carbide method of forming acetylene by putting sticks of the carbide coated with a slowly soluble glaze into cylinders containing water and attached to portable lamps. As the glaze dissolves from the surface of the stick of carbide, acetylene is generated, and the five cubic feet furnished by the stick are compressed by their own pressure, so as to supply through a suitable burner a light of more than twenty candles for about ten hours. The most immediate use contemplated by Prof. Lewes for acetylene is for enriching ordinary illuminating gas.

Cycling and the Heart.—Dr. B. W. Richardson represents cycling as differing from other exercises in that it tells primarily and most distinctly upon the heart. It produces at once a quickened circulation, though the riders may not be conscious of it; and this accounts for the astonishing journeys a cyclist can undertake, and his endurance as against sleep. Although the heart increases in action and sometimes undergoes enlargement, the author has never seen a rider embarrassed by overstrain of it, faintness, breathlessness, angina, or vertigo, so as to oblige him to dismount. Indeed, he had known a practiced rider who could climb a hill on his machine, but could not mount a flight of stairs on his feet without breathlessness and a slight palpitation; he had never seen a sudden death from cycling. He had met with instances in which, after several years of cycling, there was evidence of heart disease, with general languor and inability to sustain fatigue if exercise were again tried on the machine; and, on the other hand, he had known examples in which even an octogenarian had kept up the exercise in a moderate degree apparently with benefit to the circulation. He had seen in some cases apparent benefit arising from cycling even where there was an indication of some disease affecting the circulation, and had known good to arise from it in cases of varicose veins and of fatty degeneration, and in conditions of anæmia. In other cases excessive cycling had been a definite cause of injury to the circulation. The author believes that cycling in moderation may be permitted and even recommended to persons with healthy hearts; that it is not necessary