To do away with the necessity of filling the syphon before use, the instrument is usually made with a sucking tube, as in _Fig. 2_; in this case, all that is requisite is, to introduce the short leg, close the opening to the long one, and, by the action of the mouth, draw up the liquid until both legs are full, when, on removing the finger, the stream will flow. A very ingenious syphon of this kind is described by the German chemist Mohr; it is thus constructed:—Take a long Eau de Cologne bottle, and, with a file and turpentine, make a deep notch across, about an inch and a half from the bottom; then, with a charcoal point or pastile, or hot iron, produce a crack, and cut off the bottom, grinding it smoothly (all these manipulations are described in our last article, page 152); then take a tube bent at an angle of forty-five degrees, and, by means of a _good_ cork, perforated with a rat-tail rasp, fit it tightly in the bottom of the bottle, and add also another piece of tubing for a suction tube; the whole will then have the appearance represented in _Fig. 3_, and will form an exceedingly useful and very convenient syphon. [Illustration: _Fig. 3._] In emptying large stone bottles or carboys, the following plan may be had recourse to:—Perforate a sound cork with two openings by a rat-tail rasp, and fit, air-tight, two tubes bent as in _Fig. 4_. On blowing through the upper, the liquid will be forced to ascend and run over the bend of the other, which will then act as a syphon. This plan is exceedingly useful in emptying carboys of corrosive liquids as oil of vitriol, &c.; and if all the joints are—as they should be—air-tight, the flow may be arrested by closing the upper tube with the finger. In the figure the outer leg of the syphon is shortened to save space; in practice, it must be of sufficient length to be lower than the inner leg within the vessel. If a syphon is required frequently for decanting the same kind of liquid, it is found troublesome to be constantly filling it before each time of using it; this trouble is obviated by the use of an instrument formed with legs of equal length, which are turned up at the ends, as in _Fig. 5_; this having been filled, may be hung up in the erect position, and the liquid will not escape, but on plunging one end into a liquid, it will be found immediately to flow from the other, provided that the latter is below the level of the surface of the liquid. [Illustration: _Fig. 4._] [Illustration: _Fig. 5._]