Page:Popular Science Monthly Volume 39.djvu/586

570 was established in 1873, a system of shop-work in 1876, a laboratory of applied mechanics in 1881, the germ of a biological laboratory was introduced in 1884, and a laboratory for a course of electrical engineering was instituted in 1883. The last study is treated as dependent on mechanical engineering, and the recognition of laboratory work in mechanics as an essential feature of a proper training in any branch of the engineering profession is considered the last contribution of the Institute to the philosophy of scientific and technical education.

Petroleum Fuels.—Petroleum is defined by Prof. William Robinson as, in the widest sense of the term, comprising not only the mineral oils found in the earth's crust, but also the oils obtained by the destructive distillation of coal and bituminous shale. These complex liquid hydrocarbons vary in appearance from that of clear, light kerosene oils to heavy, dark-greenish slush or semi-fluid slime. After the volatile or lighter oils have been driven off from crude petroleum, the heavy oil left is known as residuum in America; in Russia it is called astatki. This astatki, or heavy petroleum refuse, is an excellent liquid fuel, and is at least twice as good as ordinary coal for steam-raising purposes. The light lubricating oils, intermediate oils, and kerosene or ordinary lamp oils are all being used at the present time instead of coal-gas in the cylinder of the internal-combustion engine. In some cases the heavier oils are converted into an oil-gas, which, when cooled, is admirably adapted to drive gas-engines. Other internal-combustion engines, as, for instance, the Priestman, Akroyd, and Knight engines, use common burning oils directly, and act as their own gas generators. Prof. Robinson urges that such dangerous and highly volatile hydrocarbons as benzoline, gasoline, and petroleum spirit should not be used as fuel in gas-engines. The long series of accidents so frequently attending the use of these light, inflammable vapors have done more than any other one thing to retard the development of this class of prime motors, by prejudicing the public mind against the appearance of oil in any shape or form. This volatile spirit may, however, act with safety as an evaporating agent instead of steam, as in the Yarrow spirit launches, where it is used in the internal parts, and provision is made against leakage, while ordinary burning oil generates the heat. It will thus be seen that liquid hydrocarbons, such as common petroleum oil, may be employed in prime motors as a substitute for either coal or steam or both. It is becoming generally recognized that for large powers, notwithstanding some advantages, the ordinary vaporizers in petroleum oil-engines are difficult and troublesome to work with. In fact, for large engines the practical plan obviously is to convert oil into gas by means of a gas-producer. Oil-gas, when cooled, can be used with great economy in the engine cylinder. Further, a very decided saving of fuel may be effected by this combination of oil-gas producer with the internal-combustion engine, in place of the boiler and steam-engine, in many places where suitable oil is cheap or plentiful, or where intermittent work is required. On the other hand, more heat may be produced by the direct combustion of liquid fuel with dry steam and air than by converting the oil into gas before using it as a fuel. Oil-gas is a safe, rich, permanent gas made from petroleum oil, and burned with excellent results in the gas-engine cylinder.

Improved Ventilation.—According to Mr. D. G. Hoey, the first attempt to apply really scientific principles to ventilation was made by Sir Humphry Davy in 1811, and nothing better has yet been offered. Davy proposed to ventilate the House of Commons by admitting fresh air through numerous holes in the floor and carrying off the foul air by tubes in the ceiling leading directly without, heated to promote rapidity of discharge, while the doors and windows were kept closed. The scheme failed in practical application because of defects in mechanism. A method based upon the same principles is proposed by Mr. Hoey, and has been applied in certain buildings in Glasgow. In it, for the admission of the fresh air without currents or draughts, a dado, about three feet high, is fitted at conveniently available parts around the room, with a narrow space between it and the wall. On the top of it wire gauze or perforated metal is fixed in an inclined position (to keep things from being put upon it). The fresh air is