7^4 ^f^ i^-^ lljdromelcr. 



at this period brought forward, which liavinga fet of weights 

 corvefpoiiding to the above-mentioned mixture of water and 

 proof fpirit, and the mixture of one to fix, or one in feven, 

 being that oiilv which weighed an e.xaiSl number of pounds 

 and ounces, without a fractional part, per gallon, by the 

 ftatute of the 2d of George III. this obfeure mode of afcer- 

 tainina proof was adopted. At this tinie, the efl'etts of heat 

 and cold, on the trial of the [ircngth of i'pirits by the hydro- 

 meter, had not been clearlv undcritood ; and though Clarke's 

 hydrometer, which was then adopled, bv having, in addition 

 to the weights ui'cd for afcertaining the ftrenglhs ol' i'piril.-, 

 another lot of weights called weather weights, adapted to 

 feveral temperatures, is a demonllriiiion tlial thcl'e en'c«I:ta 

 were not altogether miknown; vet they were confidcred fo 

 immaterial as not to require the mention of temperature io 

 the act of parliament. This omilhon has added confiderably 

 to the irregularities of the various hydrometers fince in uie, 

 as by it the legal Itandard for proof is rendered very uncer- 

 tain, and will, by the ordinary change of temperature, vary 

 from five to fix per cent. 



I here beg leave to quote an ohfervation of fir Charles 

 Blagden, from the Proceedings of the Royal Society in 1790, 

 in his Report on the beil Meihod of proportionating the 

 Kxcife upon Spirituous Liquors made by Defire of Govern- 

 ment: 



" By the aft of ad George III. it is ordered, that the 

 gallon of brandv or fpirits, of the ftrength of one to fix under 

 proof, iliall be taken and reckoned at fcven pounds thirteen 

 ounces (which is underftood by the trade to mean 55 of 

 heat), rience taking the weight of a gallon of water at the 

 fame heat to be 81b. 50Z. and 66 parts, the fpecific gravity 

 ot this diluted fpirit will be found 9:535 at 60 : this I'pccific 

 gravity indicates a mixture of 107 grruns of water with 100 

 grains of pure fpirit ; whence, by a computation founded on 

 the tables in this report, the fpecilic gravity of proof fpirit 

 will come out 916: but the rules of corret9.ion behmging to 

 Dicas and Qum's hydrometer give tlie fpecific gravity of proof 

 f[)irits about 922, at 55, equivalent to 1920, at 60. The 

 former, 916, correfponds to a mixture of 100 parts of fj.irit 

 •wilh 62 Dy meafure, or 75 by weight of water jj, and the lat- 

 ter, 920, to a mixture of ico parts of fpirit, and 66 by nie^- 



recours a la miithode de Fahrenheit : i"ai vu depiiis, qu'elle avuit etc mife 

 t!i ufa^e par M. BrilFon. J'cntends par cctte iiicthodc ccllc dc I'aicomc- 

 trc invfrnJ par Fahrenheit, et fuivi par Clarke et DeCaguliers." He after- 

 wards delcribes the inftrument, and condtmns it for its coiTi}ilicati'oiis, 

 and being improperly grdduated : from this it would appear that this in- 

 ftrument was invented by Fahrenheit, and not by Clarke. 



5 f""^^* 



