385 An Inquiry concerning ike Weight 



of one body, it mufl of necefTity produce the fame effeft on another, and confequentir 



that the augmentation of the quantity of latent heat muft, — in all bodies, — and in all 



cafes, — diminifli their apparent weights. 



To determine whether this is aftually the cafe or not, I made the following expe- 

 riment. 



Having provided two bottles, as nearly alike as pofTible, and in all refpeQs fimilar 

 fo thofe made ufe of in the experiments above mentioned, into one of them I put 

 4012,46 grains of water, and into the other an equal weight of mercury ; and, fealing 

 them hermetically, and fufpending them to the arms of 'the balance, I fuffered them 

 to acquire the temperature of my room, 61° ; then, bringing them into a perfeft equi- 

 librium with each other, I removed them into a room in whioh the air was at a tempe- 

 rature of 34°, where they remained twenty-four hours. — But there was not the leaft 

 appearance of either of them acquring, or lofing any weight. 



Here it is very certain, that the quantity of heat loft by the water, muft have been 

 very conliderably greater than that loft by the mercury ; the fpecific quantities of 

 latent heat in water and in mercury, having been determined to be to each other as 1000, 

 to 33 ; but this difference in the quantities of heat loft, produced no fenfible difference 

 on the weights of the fluids in queftion. 



Had any difference of weight really exifted, bad it been no more than one millionth 

 part of the weight of either of the fluids, I fhould certainly have difcovered it ; anJ, 

 had it amounted to fo much as -rs-ssoo part of that weight, I fhould have been able to 

 have meafured it ; fo fenfible, and fo veryaccurate, is the balance wjiich I ufed in 

 thefe experiments. 



I was now much confirmed in my fufpicions, that the apparent augmentation of the 

 weight of the water upon its being frozen, in the experiments before related, arofe 

 from fome accidental caufe; but I was not able to conceive what that caufe could 

 poffibly be, unlefs it were, either a greater quantity of moifture attached to the ex- 

 ternal furface of the bottle which contained the water, than to the furface of that con- 

 taining the fpirits of wine, — or fome vertical current or currents of air, caufed by the 

 bottles or one of them not being exaftly of the temperature of the furrounding at- 

 mofpherc. ^^^.^j^ ii~ii,^-j,.:ry\. .a^,.;,,;,. 



Though I had forefeen, and, as I thought, guarded fufficiently againft, thefe acci- 

 dents, — by making ufe of bottles of the.fame fize and form, — and which were blown of 

 Jhe fame kind of glafs,- — and at the fame time, — and by fuffering the bottles, in the expe- 

 riments, to'remain for fo confiderable a length of time expofed to the different degrees 

 of heat and of cold, which alternately they were made to acquire ; yet, as I did not 

 'know the relative conducing powers of ice and of fpirit of wipe %vith refpeft to heat ; 

 ■or, in other words, the degrees of facility or difficulty with which they acquire the 



temperature 



