EBUL′LIOSCOPE

Syn. Ebullition alcoholometer , Thermo-alcoholometer . “This instrument is e entially a thermometer, and its application to alcoholometry is based upon the fact that the boiling-point of a spiritous liquid is scarcely altered by the presence, within certain limits, of the substances which may be di olved in it, and which, by increasing its specific gravity, render the ordinary alcoholometers or hydrometers usele for the purpose of indicating its alcoholic richne . The ebullioscope was invented by the Abbé Bro ard-Vidal, of Toulon, and in its original form consisted of a spirit-lamp surmounted by a small boiler, into which a large cylindrical gla bulb was plunged, having an upright stem of such calibre that the quicksilver contained in them, by its expansion and ascent when heated, raised before it a little gla float in the stem, which was connected by a thread with a similar gla bead, hanging in the air. This thread pa ed round a pulley, which, turning with the motion of the beads, caused an index to move along a graduated circular scale, which represented on its face the per-centage of absolute alcohol in spirituous liquors of different boiling-points. This form of the apparatus being found inconvenient and liable to get disarranged, various improvements were made in it by MM. Conaty, Lerebour, and others. The modification of the instrument now in use, and known as Field’s Patent Alcoholometer , was made by the late Dr Ure, and can scarcely be improved on. It consists of a thermometer having a very minute bore and a large bulb, similar to that employed to determine the height of mountains from the boiling-point of water, but instead of thermometric degrees being marked upon the scale the per-centage under proof is placed on the left-hand side of the stem, and the per-centage content of proof spirit on the right-hand side. These commence at 178·5° Fahr., the temperature at which ‘proof spirit’ boils, and which here forms the bottom of the scale. The succeeding number are based upon the boiling-points of mixtures of alcohol and water. The little boiler being charged, and about a teaspoonful of salt (35 gr.) being added, to prevent lo of alcohol by evaporation, the thermometer is set in its place, and the spirit-lamp lighted. When the mercury begins to rise out of the bulb of the thermometer, the ‘damper-plate’ is pushed in a little way, to moderate the heat. The eye is now kept steadily on the instrument, and as soon as the liquor boils freely, and the mercury becomes stationary in the stem, the indication is carefully noted, and the damper-plate pushed home to extinguish the flame. “The ebullioscope is adjusted to the mean boiling-point of water under an atmospheric pre ure of 29·5 inches. When the pre ure is either higher or lower, both water and alcohol boil at a somewhat different temperature, to meet which a barometrical equation is attached to the thermometer by means of a small subsidiary scale. It is therefore nece ary, prior to commencing the operation of testing any liquor, to charge the little boiler with pure water only, and to fix the thermometer in its place. When the water boils freely, the mercury becomes stationary in the stem, exactly opposite the true barometrical indication at the time. Should this be against the line 29·5, no correction will be required; but should it stand at any other line, above or below, then the various boiling-points will bear reference to that boiling-point only. In the latter case, the boiling-point of the water on the barometrical indicator must be set against the boiling-point of the liquid on the scale, when opposite the line—29·5 will be found the true strength. Thus:—the barometer being at 30 inches, and the indication or boiling-point being 72 u. p., 30 on the indicator must be placed against 72 u. p. on the thermometer, when against the line of 29·5 will be seen 69·6 u. p., the real strength of the sample tested. “When a spirit is stronger than the ‘excise proof,’ its boiling-point varies too little with its alterations of strength to render the ebullioscope of much practical value. To make it applicable to the stronger spirits, it is therefore nece ary to dilute them with exactly their own bulk of pure water before testing them, and then to double the resulting indication, as suggested by Dr Ure. Our own plan is always to do this when the spirit is stronger than 20 u. p. “By means of the ebullioscope the alcoholic content of beer, wines, and spirits, of every variety and cla , may be readily determined with sufficient accuracy for all practical purposes; and by methods which we shall hereafter point out, the amount of saccharine extractive, or sugar, in cordialised spirit, malt liquors and wines, may also be ascertained. “The ebullioscope (Field’s Alcoholometer ) employed by us in numerous and extensive investigations connected with public hygiène, was made by Mr Long, of Little Tower Street, and is an instrument which should be in the hands of every wine and spirit merchant and licensed victualler, as well as every private gentleman who feels interested in the quality of the liquors in his cellar. The instrument is accompanied by a useful little pamphlet of directions and tables, which has been very accurately got up, as we understand, by the late Dr Ure, expre ly for Mr Long.” (A. J. Cooley.)