3& Relation letwecn. the Specif c Gravities and 



bf any liquid, we indicate nothing with respect to its real 

 quantity, unless we at the same time express the tempera-^ 

 ture at which it is to be measured. 



§ 9. If an equal change took place in the bulks of alco- 

 Lol, and of water, and of every compound of them, by the 

 same elevation or depression of temperature, the application 

 of the necessary correction for this circumstance would be 

 still easy. The difference in this respect is, however, very 

 considerable: water increases only about l-300dth of its 

 bulk bv an elevation of its temperature from 40° to 80° of 

 Fahrenheit's thermometer, whilst alcohol would, by a simi- 

 lar change of temperature, increase in measure no. less than 

 1— tsd of the whole, or seven times as much as the other ; 

 and liquors of intermediate strengths would be affected in 

 some intermediate degree. To estimate, therefore, the dif- 

 terence in the measure produced by this cause, we must 

 know the strength of the liquor; whilst this, on the other 

 hand, is only to be determined with reference to the former. 



§ 10. The effect of which we are next to speak is of a 

 still more curious nature. When two fluids which are ca- 

 pable of chemical combination are mixed together, it gene- 

 rally happens that either heat or cold is produced, the tem- 

 perature of the compound differing fron\ the mean tempe- 

 rature of its ingredients. The former is most commonly 

 the case; and, when so, it happens in the greater number 

 of instances, and perhaps in all, that a diminution of the 

 bulk or measure of the compound also takes place, whicli 

 is proportional to the heat so produced : probably in conse- 

 quence of this separation of caloric* 



If 1 8 gallons of water be mixed with the like quantity of 

 the strongest spirit of wine, the mixture will become consi- 

 derably warmer, and we shall only get about 3 J gallons of 

 the dduted spirit instead of 36 : and this kind of effect is 

 also produced in less degree by the addition of water to any 

 weaker spirit, or the mixture of two such liquors of dif- 

 ferent strengths ; the resulting compound being always 

 found to occupy less space than the substances forming it 

 did when separate; and its specific gravity being therefore 

 greater than would be inferred by mere arithmetical calcu- 

 lation from those of its ingredients. This " concentration," 

 as it is very properly called, must of course be considered 

 in the estiniati(.>n of the strength from the specific gravity 

 of a liquor ; and the consideration of it is attended with the 

 same difficulty, as has already been mentioned in the last 

 section, with respect to tlie effect produced by change of 

 temperature . 



§11. 



