ALCOHOL 47 



liquids was 60 F. ; and of course, in using it, it is necessary that the density should 

 be observed at that temperature. 



In order to convert the statement of the composition by volume into the content by 

 weight, it is only necessary to multiply the per-centage of alcohol by volume by the 

 specific gravity of absolute alcohol, and then divide by the specific gravity of tho 

 liquid. 



It has been thought desirable to retain tho following remarks by Dr. Uro, and to 

 give Mr. Gilpin's Tables in addition to the others. 



The importance of extreme accuracy in determining the density of alcoholic mix- 

 tures in the United Kingdom, on account of the great revenue derived from thorn to 

 the State, and their consequent high price in commerce, induced the Lords of the 

 Treasury a few years ago to request the Royal Society to examine the construction 

 and mode of applying the instrument now in use for ascertaining and charging the 

 duty on spirits. This instrument, which is known and described in tho law as Sikes's 

 hydrometer, possesses, in many respects, decided advantages over those formerly in 

 use. The committee of the Royal Society state, that a definite mixture of alcohol 

 and water is as invariable in its value as absolute alcohol can be ; and can be more 

 readily, and with equal accuracy, identified by that only quality or condition to which 

 recourse can be had in practice, namely, specific gravity. The committee further 

 proposed, that the standard spirit bo that which, consisting of alcohol and water alone, 

 shall have a specific gravity of 0'92 at the temperature of 62 F., water being unity at 

 the same temperature ; or, in other words, that it shall at 62 weigh ^ths or ff ths 

 of an equal bulk of water at the same temperature. 



This standard is rather stronger than the old proof, which was jgths or 0-923 ; or 

 in the proportion of nearly 1*1 gallon of the present proof spirit per cent. The pro- 

 posed standard will contain nearly one-half by weight of absolute alcohol. The 

 hydrometer ought to be so graduated as to give the indication of strength ; not upon 

 an arbitrary scale, but in terms of specific gravity at the temperature of 62. 



The committee recommend the construction of an equation table, which shall 

 indicate tho same strength of spirit at every temperature. Thus in standard spirit 

 at 62 the hydrometer would indicate 920, which in this table would give proof 

 spirit. If that same spirit -were cooled to 40, the hydrometer would indicate 

 some higher number ; but which, being combined in the table with the temperature 

 as indicated by the thermometer, should still give proof or standard spirit as tho 

 result. 



It is considered advisable, in this and the other tables, not to express the quality 

 of the spirit by any number over or under proof, but to indicate at once the number 

 of gallons of standard spirit contained in, or equivalent to, 100 gallons of the 

 spirit under examination. Thus, instead of saying 23 over proof, it is proposed 

 to insert 123 ; and in place of 35'4 under proof, to insert its difference to 100, 

 or 64-6. 



It has been considered expedient to recommend a second table to be constructed, 

 so as to show the bulk of spirit of any strength at any temperature, relative to a 

 standard bulk of 100 gallons at 62. In this table a spirit which had diminished in 

 volume, at any given temperature, 0'7 per cent., for example, would bo expressed by 

 99-3 ; and a spirit which had increased at any given temperature 0'7 per cent., by 

 100-7. 



When a sample of spirit, therefore, has been examined by the hydrometer and 

 thermometer, these tables will give first the proportion of standard spirit at the ob- 

 served temperature, and next the change of bulk of such spirit from what it would be 

 at the standard temperature. Thus at the temperature of 51, and with an indication 

 (specific gravity) of 8,240, 100 gallons of the spirit under examination would be shown 

 by the first table to be equal to 164-8 gallons of standard spirit of that temperature ; 

 and by the second table it would appear that 99-3 gallons of the same spirit would 

 become 100 at 62, or in reality contain tho 164'8 gallons of spirit in that state only 

 in which it is to be taxed. 



But as it is considered that neither of these tables can alone be used for charging 

 the duty (for neither can express the actual quantity of spirit of a specific gravity of 

 0-92 at 62 in 100 gallons of stronger or weaker spirit at temperatures above or below 

 62), it is considered essential to have a third table, combining the two former, and 

 expressing this relation directly, so that upon mere inspection it shall indicate the 

 proportion of standard spirit in 100 gallons of that under examination in its then 

 present state. In this table tho quantities should be set down in the actual number 

 of gallons of standard spirit at 62, equivalent to 100 of tho spirit under examination ; 

 and the column of quantities may bo expressed by tho term value, as it in reality ox- 

 presses the proportion of the only valuable substance present. 



The following specimen Table has been given by tho committee : 



