EBULLITION" ALCOHOLOMETER 



183 



seale. The numbers on this scale represent percentages of absolute alcohol, so that 

 the number opposite to which the index stops, when the liquor in the cylinder over 

 the lamp boils briskly, denotes the percentage of alcohol in it. 



Dr. Ure introduced another form of instrument (Jig. 773). It is thus described by 

 the inventor : 



It consists, 1, of a flat spirit-lamp A, surrounded by a saucer for containing 

 cold water to keep the lamp cool, should many experiments require to be made in suc- 

 cession ; 2, of the boiler B, which fits by its bottom cage c, upon the case of the 

 lamp. At the point c, is seen the edge of the damper-plate for modifying the flame 

 of the lamp, or extinguishing it when the experiment is completed. D is the thermo- 

 meter, made with a very minute bore, in the manner of the Rev. Mr. Wollaston's in- 

 strument for measuring the height of a mountain by the boiling point of water on its 

 summit. The bottom of the scale in the ebullition thermometer, is marked p for 

 proof on the left side, and 100 (of proof spirit) on the right side. It corresponds 

 to 178-6 Fahr. very nearly, or the boiling point of alcohol of 0*920 specific gravity. 

 The following table gives the boiling points corresponding to the indicated densities : 



Temp. Fahr. 

 178-6 

 179-75 

 180-4 

 181-0 

 183-4 



Specific Gravity 

 0-9200 P. 

 0-9321 10 U. P. 



0-9420 

 0-9516 

 0-960 



20 

 30 

 40 



Temp. Fahr. 

 185-6 

 189-0 

 191-8 

 196-4 

 202-0 



Specific Gravity 

 0-3665 50 U. P. 

 0-9729 60 

 0-9786 

 0-9850 



0-992 



70 

 80 

 90 



The above table is the mean of a great many experiments. When alcohol is 

 stronger than 0'92, or the excise proof, its boiling point varies too little with its 

 progressive increase of strength to render that test applicable in practice. In fact, 

 even for proof spirits, or spirits approaching in strength to proof, a more exact 

 indication may be obtained by diluting them with their own bulk of water, before 

 ascertaining their strength and then doubling it. 



The boiling point of any alcoholic liquor is apt to rise if the heat be long continued, 

 and thereby to lead into error in using this instrument. This source of fallacy may 

 be in a great measure avoided by adding to the liquor in the little boiler about a 

 teaspoonful (thirty-five grains) of common culinary salt, which has the curious effect 

 of arresting the mercury in the thermometer at the true boiling point of the spirit, 

 wine, or beer, to enable a correct reading to be had. The small measure marked M 

 holds the requisite quantity of salt. 



The thermometer is at first adjusted to an atmospheric pressure of 29'5 inches. 

 "When that pressure is higher or lower, both water and alcohol boil at a somewhat 

 higher or lower temperature. In order to correct the error which would hence 

 arise in the indications of this instrument under different states of the weather, 

 a barometrical equation is attached, by means of the subsidiary scale E, to the ther- 

 mometer D. 



Having stated the principles and the construction of the ebullition alcoholometer, 

 I shall now describe the mode of its application. 



First. Light the spirit-lamp A. 



Second. Charge the boiling vessel B, with the liquid to be tested (to within an 

 inch of the top), introducing at the same time a paper of the powder ; then place the 

 vessel B (the damper-plate being withdrawn) on to the lamp A. 



Third. Fix the thermometer D on the stem attached to B, with its bulb immersed 

 in the liquid. The process will then be in operation. 



The barometrical scale indicated on the thermometer is opposite the mean boiling 

 point of water. Prior to commencing operations for the day, charge the boiler B 

 with water only, and fix the instrument as directed ; when the water boils freely, the 

 mercury will become stationary in the stem of the thermometer, opposite to the true 

 barometrical indication at the time. Should the mercury stand at the line 29'5 this 

 will be the height of the barometer, and 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. 



In testing spirituous or fermented liquors of any kind, when the mercury begins 

 to rise out of the bulb of the thermometer into the stem, push the damper-plate half- 

 way in its groove to moderate the heat of the flame. When the liquor boils freely 

 the mercury will become stationary in the stem ; and opposite to its indication, on the 

 left, the underproof percentage of spirit may be read off at once, if the barometer 

 stand that day at 29-5 inches ; while on the right-hand scale, the percentage of 

 proof spirit is shown ; being the difference of the former number from 100. The 

 damper-plate is to be immediately pushed home to extinguish the flame. 



The alcoholometer will by itself only indicate the percentage of alcohol contained 



