The boiling-point of water contained in ordinary vessels may be raised considerably above 212° Fahr., by the addition of saline matter, as will be seen in the following table, extracted from Mr C. G. Williams’s excellent ‘Handbook of Chemical Manipulation,’—

Table II.—Boiling-points of Saturated Solutions
of various Salts at the ordinary Atmospheric
Pressure. By C. G. Williams.

Name of Salt.Boiling-point.
Chloride of calcium355°Fahr.
Acetate of soda256”
Nitrate of soda246”
Sal-ammoniac236”
Common salt224”
Cream of tartar214”

The above solutions are suitable for chemical baths. With the exception of the first, they furnish in their boiling-points temperatures, as nearly as can be obtained, 10° above each other. They were chosen by Mr Williams because, in ‘fractionating’ volatile substances, it is usual to separate the distilled products by differences of temperature equal to 10° Fahr. In long operations it is found inconvenient to employ a saturated saline solution for a bath (by which the highest temperature would be obtained), as the constant evaporation of the water induces the crystallisation of

the salt. It is hence usual to keep it considerably below that point.

The following table, compiled chiefly from the pages of Dr Miller’s ‘Elements of Chemistry,’ gives the boiling-points of several interesting substances.

Table III.—Boiling-points of various Liquids
at the ordinary Atmospheric Pressure.

Name of
Substance.		Boiling-point.
Liquid carbonic acid-108°Fahr.
Liquid sulphurous acid+ 17·6”
Chloric ether51·9”
Aldehyd69·4”
Ether94·8”
Bisulphide of carbon118·5”
Bromide145·4”
Wood spirit149·9”
Alcohol (sp. gr. ·815)173·1”
Benzol176·8”
Dutch liquid184·7”
Acetic acid243·1”
Sulphur (melted)609·”
Mercury662·”

EBUL′LIOSCOPE. Syn. Ebullition alcoholometer, Thermo-alcoholometer. “This instrument is essentially 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 dissolved in it, and which, by increasing its specific gravity, render the ordinary alcoholometers or hydrometers useless for the purpose of indicating its alcoholic richness. The ebullioscope was invented by the Abbé Brossard-Vidal, of Toulon, and in its original form consisted of a spirit-lamp surmounted by a small boiler, into which a large cylindrical glass 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 glass float in the stem, which was connected by a thread with a similar glass bead, hanging in the air. This thread passed 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 loss 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 pressure of 29·5 inches. When the pressure 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 necessary, 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.