gSa An Inquiry concerning the Weight 



vince me more and more, that a lody acquires no additional tveight upon heing heated, 

 or rather, that heat has no efFeft whatever upon the weights of bodies, 1 have been To 

 fenfible of the dehcacy of the inquiry, that I was for a long time atraid to iorm a de- 

 cided opinion upon the fubjcfl. 



Being much ftruck ^ith thfc experiments rftcbrdcd irt the Trinfaflsons of the Royal 

 Society, Vol. LXXV. made by Dr. 'Fordyce, upon the weight faid to be acquired by 

 water upon being frozen; and being poffefTed of an excellent balance, belonging to 

 His mojl Serene Highnefs the EleBor Palatine Duke of Bavaria ; early in 

 the bigitoiifeg of the winter of the^ yecff i/S/, — as foon as the cold was fuiEciently 

 intenfe for my purpofe, — I fet about to repeat thofe experiments, in order to convince 

 myfelf whether the very extraordinary faft related, might be' depended on ; and, with 

 a view to removing, as far as was in my power, every fource of enor and deception, 

 I proceeded in the following manner. 



Having provided a number of glafs bottles, of the form and fij'.e of what in England 

 is called a Florence flafk, — blown as thin as poffible, — and oi the fame (hape and dimen- 

 fions, I chofe out from amongft them two, which, after ufing every method I could 

 imagine of comparmg them together, appeared to be fo much alike as hardly to be dif- 

 tinguiflied. 



Into one of thefe bottles, which I" Ihall Call A, I put 4107,86 grains Troy of pure 

 diftilled water, which filled it about halt full ; and into the other, B, I put an equal 

 weight of weak fpirit of wine ; and, fealing both the bottles hermetically, and wafhifig 

 them, and wiping them perfeftly clean and dry on the outfide, I fufpended them to the 

 arms of the balance, and placed the balance in a large room, which for foine weeks had 

 been regularly heated every day by a German ftove, and in which the air was kept up 

 to the temperature of 61' of Fahrenheit's thermometer, with verv little variation. 

 Having fuffered the bottles, with their contents, to remain in this fituation till I con- 

 ceived they muft, have acquired the temperature of the circumambient air, I wiped them 

 afrefii, with a very clean dry cambric handkerchief, and brought them into the moft 

 exaft equilibrhim pofhble, by attaching a fmall piece of very fine filver wire to the 

 arm of the balance to which tl;ie bottle which was the lighteft was fufpended. 



Having fufiFered the apparatus to remain in this fituation about twelve hours longer, 

 and finding no alteration in the relative weights of the bottles, — they continuing all this 

 time to be in the moft perfeft equilibrium, — I now removed them into a large unin- 

 habited room, fronting the north, in which the air, which was very quiet, was at the 

 temperature of 29°, F ; the air without doors being at the fame time at 27° ; and, going 

 out of the room, and locking the door after me, I fuffered the bottles to remain forty- 

 eight hours, undifturbed, in this cold fituation, attached to the arms of the balance as 

 before. 



