_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. ---------------+------------+----------------+------------ | Alcohol | | Alcohol Boiling point. | per cent. | Boiling point. | per cent. Fahr. | by volume. | Fahr. | by volume. ---------------+------------+----------------+------------ 205·34 | 5 | 179·96 | 55 199·22 | 10 | 179·42 | 60 195·8 | 15 | 178·7 | 65 192·38 | 20 | 177·62 | 70 189·50 | 25 | 176·54 | 75 187·16 | 30 | 175·46 | 80 185· | 35 | 174·92 | 85 183·38 | 40 | 174·2 | 90 182·12 | 45 | 173·14 | 95 181·58 | 50 | 172· | 100 ---------------+------------+----------------+------------ TABLE V.——_Showing the_ BOILING POINTS _of ‘under proof’ spirit._ By Dr URE.