On the Hydromefer. J^J 



meter, it then appears to be full one and a half per cent, 

 ftronger than whtrn it was fliipned, and will now be found to- 

 be 11 per cent, over proof. Should this fpirit be a foreign 

 one, viz. brandy or geneva, it nnift pay the entire augment- 

 ation duty of II per cent.; whereas, if the temperature was 

 fnfficiently difcriminated, it fliould have paid no augmenta- 

 tion duty whatever. 



That this cafe is not merely a fuppofition, is, I believe, 

 well known to feveral refpeclable merchants in London, to 

 whom confignments of foreign fpirits have been made from 

 Ireland, ancTwho, in feveraf inltances, have been obliged to 

 pay this augmentation duty of ii per cent. Here, therefore, 

 the inrirument proves its own errors; nor can additional 

 weights remedy it. 



The principle on which it is conftrufted fuppofes that the 

 ratio of expanfion by heat is the fame in (Irong as in weak 

 fpirits ; the fame weight for temperature is therefore applied 

 to both : this is tolallv erroneous, and is deuionftrable thus: 

 Suppofe a weak fpirit to be tried, the fpecific gravity of 

 which, at the temperature of ^^, is 960-48, let the tempe- 

 rature be incrcafcd to 70, the fpecific gravity will be 948-13 ; 

 the diminution, confequently, is 12-35. 



Suppofe next, the fpirit under trial to be a ftrongone, and 

 is per fpecific gravity at 35, 843*49 ; increafe the tempera- 

 ture, as in the firft, to 70, the fpecific gravity will be only 

 827-01 : diminution in this fpirit 16-48 ; difference in the ratio 

 of expanfion 4- 13 ; this difference making full three per cent. 

 by the hydrometer, and thus demonftrating a radical Atiedi 

 in the initrument which cannot le cured hy add'Uhnal weights, 

 'Vht fpirituous liquors of commerce being mixtures of pure 

 fpirit and water, and the value of this, and the duty to be 

 paid on it, depending on the quantities of the former which 

 are contained in the mixture, it becomes neceflary to afeertain 

 the proportion in which it enters into every fuch mixture. 



The eafiell and mod expeditious mode of afcerlaining this 

 is by an hydrometer, which acts on the following well-knowu 

 principles of hydrodatics. ' 



7V lolicl body dcfcends in a liquid, becaufc it is heavier than 

 an e(]ual bulk of the \yc\\\\<\ : and it defcends with a force or 

 weight equal to the excels of its own weight, over the weight 

 of an ccjual bulk of the liquid; or, if it be lighter than an 

 equal bulk of the liquid, it alcends wiih a force proportitmed 

 to the difierencc of weights ; but if it be of the fame weight 

 as an equal bulk of the liquid, it will remain where it is 

 placed. 



Ilence 



