Revenue Method. The following is the method adopted in the Inland Revenue and Customs Laboratories for the estimation of the per-centage of alcohol in wines, liqueurs, &c. A measure flask is filled up to a mark on its neck, with the wine, which is then carefully transferred to a distilling flask or retort, the traces of wine remaining in the former vessel being rinsed out with small quantities of distilled water, and the rinsings added to the wine in the latter vessel. About two thirds of the contents of the retort are then distilled over into the clean measure flask, and made up to the original bulk with distilled water, at the same temperature as the sample was previous to distillation. The strength is then taken by Sykes’ hydrometer, and this (if u. p.) deducted from 100, gives the per-centage of proof spirit in the wine. Thus:—

Strength of distillate = 74·6 u. p. = 25·4 per cent. proof spirit.

b. From the Temperature of the Vapour, as originally proposed by Gröning. The bulb of a thermometer is thrust through a cork into the head of the still, or other vessel employed, and the temperature of the vapour in which it is immersed being noted, is sought in the following table:—

Table III.—Showing the Alcoholic Content, by Volume, of Boiling Spirits, and of their Vapour, from the Temperature of the latter, as observed by a Thermometer. By Gröning.

Temperature of the Vapour. Fahr.Alcoholic content of the Distillate per cent.Alcoholic content of the Boiling Liquid per cent.Temperature of the Vapour. Fahr.Alcoholic content of the Distillate per cent.Alcoholic content of the Boiling Liquid per cent.
170·09392189·87120
171·89290192·06818
172·09185194·06615
172·8901⁄280196·46112
174·09075198·65510
174·68970201·0507
176·08765203·0425
178·38550205·4363
180·88240207·7282
183·08035210·0131
185·07830212·000

This method is admirably adapted to the purposes of the distiller and rectifier, as it furnishes a ready means of approximately determining the strength of the spirit passing over, at every part of the process of distillation, as well as that of the wash left in the still.

c. From the BOILING POINT, as originally proposed by M. l’Abbé Brossard-Vidal. This method is founded on the fact, that the boiling points of mixtures of alcohol and water, unlike water alone, are scarcely disturbed by the addition of saline, saccharine, or extractive matter within certain limits. It hence offers a ready means of determining the proportion of alcohol present in spirits, wines, fermented

liquors, &c., with sufficient accuracy for all ordinary purposes. In applying it, a thermometer, with a large bulb and a narrow bore, and a movable scale graduated from 180° to 212° Fahr., is usually employed. Before using it as an alcoholometer, it is set, with its bulb immersed, in a small metallic boiler (brass or copper) containing distilled water, which is then raised to the boiling-point, and the 212° of the scale accurately adjusted on a level with the surface of the mercury, should it vary from that point. This is necessary on account of variations of atmospheric pressure causing corresponding variations of the boiling-points of liquids. It is then ready for several hours’ operations, and, generally, for an entire business day, without further adjustment. The little boiler is next filled with the liquor to be examined, and the lamp again lighted. The temperature as shown by the scale of the instrument at the commencement of full ebullition being ascertained, may be sought in one of the following Tables, against which the alcoholic content of the liquor will be found (nearly).

Table IV.—Exhibiting the BOILING POINTS of Mixtures of Alcohol and Water of the given strengths. By Gröning.

Boiling point. Fahr.Alcohol per cent.
by volume.		Boiling point. Fahr.Alcohol per cent.
by volume.
205·345179·9655
199·2210179·4260
195·815178·765
192·3820177·6270
189·5025176·5475
187·1630175·4680
185·35174·9285
183·3840174·290
182·1245173·1495
181·5850172·100