refpcEling Heat or Caloric, l6^ 



to fink the bladder in the water, the fpecific gravity of the 

 water being known. But if I weigh, in water, any fubftance 

 containing an unknown quantity of heat, and find that, upon 

 adding a known bulk of heat to the body, it will then require 

 a lefs weight to make it (ink, I am to draw no inference re- 

 fpe<Sling the weight of the caloric that ha« been added ! ! Is 

 this reafonable ? Should philofophers ftop (hort in this man- 

 ner, and not feize upon the truth which fuch efle6ts exhibit 

 to them ? Is it not obvious, in all experiments which have 

 for their objeft the determining the fpecififc gravity of any 

 body in difierent temperatures, that they are doing notliing 

 but weighing comparative quantities of heat, by obferving 

 how much water is difplaced bv thofe quantities ? 



Though I think the truth I have juft ffcated is felf- evident, 

 I hope I (liall not be thought tirefome if I endeavour to fet 

 it in a clear point of view by an illuftration. 



If I fufpcnd a piece of metal in water at one end of a ba- 

 lance, and if to this metal I join a fmall bit of any fubftance 

 lighter than water, fiiy a bit of cork, will not the mafs, by 

 having its abfolute gravity incrcafed, have become fpccificallv 

 lighter ? I am now confidering the metal and cork as one 

 compound bodv. In this cafe no one hefitates in admittincr 

 that the addition of the cork, though poifefling abfolute gra- 

 vity, is the caufe of the compound body appearing lighter 

 when weighed in water ; a medium more rare than one of 

 the ingredients, but denfer than the other : but if heat injhad 

 of CQrh bad heen added to the metal, ivould not the effeB have 

 been the fame, an increafe of volume and a diminution of 

 fpecific gravity ? And for the fame reafon too, the metal 

 being heavier but the heat lighter than water. 



Let us reverie the cafe. — ^A compound body, iron and 

 cork, poiTefles a certain fpecific gravity. Remove the cork, 

 that is, take awav from the mafs 4 portion of its abfolute 

 bulk and weighty and on weighing what remains it is found 

 to be increafed in weight — in water. 



Yet, if I detach from a piece of gold, filver, platlna, copper, 

 a certain quantity of heat, by mechanical means, and thereby 

 reduce its volume, I am not to conclude, though I find ittj 

 (jiecific gravity increafed, that the matter exprciVed poiVefled 



X % abfolute 



