1 64 Examhiaikn gJ tht received DoSirlnes 



^bfolute gravity, though lefs fpecifically than that of water f 

 Is this confiftent with loLmd phy'fical principles ? I think not: 

 for the {kme effedls Ihould always be afcribed to one caufe. 



It is admitted on all hands that caft metals^ that is, metals 

 in their largeft natural volume, are fpecifically lighter than 

 when drawn into wire or rolled into plates, that is^ -Cvhert re-* 

 duced in fize, by haying fomcthing feparated from them, 

 namely^ heat. 



If a piece of denfe wood, that has been foaked in oil or- 

 alcohol, be weighed in water ; and if a portion of the imbibed 

 liquid be cxpreffed, and the wood be again weighed, its fpe- 

 cific gra.vity will be found to have increaftd ; becaufe the fluid- 

 expelled from it was lighter than water. Every one can fee^ 

 and feel the oil or alcohol dnven out of union with the wood ;. 

 and every one may feel the heat driven out of metals by pafT- 

 ing them through rollers. Is it becaufe heat is only cognif-* 

 able, in the firft inftance, by one grofs fenfe that its exift- 

 ence as matter is denied ? It may be feen aS well as felt, as. 

 I have Ix'fore had occafion to remark ; for when driven from 

 one body, the volume of which is in confequence diminiilied, 

 it enters into others, and theirs become vijibly enlarged. If 

 it were not fo, even the common thermometer could have no 

 exiftence. 



I (hall here mention the diflferent fpecific gravities of a few- 

 metals in their caft ftate, and when a portion of heat hasi 

 been ft,'parated from them, by their molecul^e being brought 

 fo much clofer together, by mechanical means, as to increafe 

 the power of aggregation, or, in other words, to diminifh 

 their capacity for heat. 



Caft. Hammered. Rolled. Drawn into wire. 



The fa<^ is, I fufped, univerfally true, that where the fpe^ 

 cific gravity of a body is. diminifhed, its abfolute gravity is 

 and muft biE izicreafed j and thcfe terms ought always to be 



confidered 



