Liquids (Decanting, Straining, And Filtering Of). The decanting of liquids is, under ordinary circumstances, an operation sufficiently simple to require no explanation; but the ease and certainty with which it can be performed depend entirely upon the form of the vessel from which the liquid is poured, the adhesion existing between liquids and solids giving rise to a tendency in the former to run down the outside of the vessel; and, if the latter is nearly full, or very large in circumference, or the sides approach the perpen-dicular direction, this accident almost always occurs. The difficulty of returning a glass of wine to the decanter, or of pouring from full tumbler into another, are wellknown examples of this inconvenience
Advantage may, however, be taken of the adhesion of liquids to solids, and by it the former may be led into the required direction. This cannot be better illustrated than by a description of the means l>y which a glass of wine may be returned, without spilling, to the decanter. If a teaspoon is dipped into the wine, so as to become wetted with it, and then held perpendicularly with the bowl downwards, and the point over, but not touching, the entrance Into the decanter, and the edge of the glass be made to touch the back of the spoon, it will be found, on inclining the former, that the wine, having a perpendicular solid body to adhere to and run down, will do so in preference to trickling along the oblique outer surface of the wineglass; and, in this mode, a liquid may be poured steadily out of any similar vessel with so little disturbance not to agitate any sediment that may exist in it. In the laboratory of the chemist, a piece, of glass rod is usually employed for this purpose ; but a spoon, or pencil, or any similar substance having a surface capable of being wetted by the liquid, answers well.
If, however, the vessel out of which it is wished to decant is large, very full, or the sides, on pouring, are nearly perpendicular, the plan is not successful; thus, it could not be employed in aiding the transfer of the liquid from one full tumbler to another. Even this may be accomplished without the aid of a funnel, or without spilling, by preventing the adhesion of the liquid to the edge or side of the vessel out of which it is poured, which may be readily done by greasing the rim, when it will he found quite practicable to pour out of a nearly full tumbler without spilling.
In many instances, the employment of a syphon in decanting will be found very advantageous, particularly when the containing vessel is large, and cannot be readily moved, or when there is any sediment which it is desirable not to disturb. The most simple form of this instrument consists of a tube, bent as in fig. 1, with one leg shorter than the other; this may be made of glass pewter, or, in fact, of any kind of stiff tubing that will retain its form - a piece of gutta-percha pipe, carefully bent by a moderate warmth, whilst a piece of stout cord is in the interior to prevent the sides closing together, answers very well. Before use, the syphon must be filled with liquor; this is best accomplished by turning it upside down, with the opening to the short leg raised on a level with that of the long one, when the liquid should be poured into the former. When both legs are tilled, they should be closed with the fingers: the shorter leg introduced into the liquid it is wished to draw off; and the opening of the longer leg brought to a lower level than that of the shorter, and on removing the fingers, the liquid will flow as in fig. 1, until it is below the level of the short leg. If the syphon is made of small tubing, or is lessened at the openings so as not to exceed a quarter of an inch in diameter, there will be no occasion to close the end of more than one leg with the finger, as the liquid will not flow when it is brought to the proper position, unless both orifices are open ; and thus the necessity of plunging the finger into the liquid is obviated, and the syphion can also be used with a narrow-necked bottle, into "which the hand could not be passed.
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 ; 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 the suction
Fig. 3. tube; the whole will then have the appearance represented in fig. 3, and will form an exceedingly useful and very convenient syphon.
Fig. 4. 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, etc.; 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 prac-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 tame of using ; this trouble is obviated by the use of an instrument formed with lags of equal length, which are turned up at the ends, as in fig. 5 ; this, having been tilled, 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 ether, provided that the latter is below the level or the surface of the liquid.