426 , PHILOSOPHICAL TRANSACTIONS. [aNNO 1794. 



XX. Tobies for Reducing the Quantities by Weight, in any Mixture of Pure 

 Spirit and PVater, to those by Measure ; and for Determining the Proportion, 

 by Measure, of each of the two Substances in such Mixtures. By Mr. George 

 Gilpin, Clerk to the R.S. p. 275. 



These tables are founded on ihe experiments of which the results were given 

 in the report and supplementary report on the best method of proportioning the 

 excise on spirituous liquors. They are computed for every degree of heat from 

 30° to 80°, and for the addition or subtraction of every one part in 100 of water 

 or spirit ; but as the experiments themselves were made only to every 5th degree 

 of heat, and every 5 in the 100 of water or spirit, the intermediate places are 

 filled up by interpolation in the usual manner, with allowance for 2d differences. 



Every table consists of 8 columns, and there are 2 tables for every degree of 

 heat. In the first column of the first of the 2 tables, are given the proportions 

 of spirit and water by weight, 100 parts of spirit being taken as the constant 

 number, to which additions are made successively of one part of water from 1 to 

 99 inclusively. The first column in the 2d table has 100 parts of water for 

 the constant number, with the parts of spirit decreasing successively by unity, 

 from 100 to 1 inclusively. The 2d column of all the tables gives the specific 

 gravities of the corresponding mixtures of spirit and water in the first column, 

 taken from the table of specific gravities in the supplementary report, the inter- 

 mediate spaces being filled up by interpolation. In the 3d column 100 parts by 

 measure of pure spirit, at the temperature marked on the top of every separate 

 table, is assumed as the constant standard number, to which the respective quan- 

 tities of water by measure, at the same temperature, are to be proportioned in 

 the next column. The 4th column therefore contains the proportion of water 

 by measure, to 100 measures of spirit, answering to the proportions by weight 

 in the same horizontal line of the first column. The 5th column shows the 

 number of parts which the quantities of spirit and water contained in the 3d 

 and 4th columns would measure when the mixture has been completed ; that is, 

 the bulk of the whole mixture after the concentration, or mutual penetration, 

 has fully taken place. The 6th column, deduced from the 3 preceding ones, 

 gives the effect of that concentration, or how much smaller the volume of the 

 whole mixture is, than it would be if there was no such principle as the mutuaJ 

 penetration. The 7th column shows the quantity of pure spirit by measure, at 

 the temperature in the table, contained in 100 measures of the mixture laid 

 down in the 5th column. Lastly, the 8th column gives the decimal multiplier, 

 by means of which the quantity by measure of standard pure spirit, of .825 

 specific gravity at 6o° of heat, may at once be ascertained, the temperature and 

 specific gravity of the liquor being given ; pursuant to the idea suggested in the 

 report, that " the simplest and most equitable method of levying the duty on 



