On the Caufes of Elajl'iclty. 243 



of perfe(?t folution ; neverthelefs it is of great importance, by- 

 rendering rain or river water as clear and tranfparent as hard 

 water (fpring water), to preclude in moft cafes the neceflity 

 of ufing the latter, which generally abounds with pernicious 

 impregnations collefted from the bowels of the earth by 

 chemical decompofition. 



XII. A curjory Vienv of fome of the late Di/coveries in 

 Science. 



B. 



[Continued from Page 132.] 



^ARRUEL has made refearches refpefting the caufe of 

 elafticity, which he afcribes to two principles: i. "Every- 

 body in nature," fays he, " is porovis, and thefe pores are 

 proportioned to the denfity of the fubftance : 2. Thefe pores 

 are filled with different fluids, and principally with caloric. 

 But caloric pofTefles a ftrong repulfive force ; from which it 

 follows, that, when an elaftic body is comprefled, the caloric 

 in its pores drives back by its repulfive power the difplaced 

 parts, and brings them to their former fliate." Libes, who 

 has examined the fame fubjeft, makes elafi:icity to depend 

 on caloric interpofed either between the moleculae of the 

 bodies, or combined with them, and at the fame time on. 

 the attraftive force of thefe moleculse. " This being pre- 

 mifed," fays he, " I fay, that the rcfi:oration of folid bodies 

 after compreflion is a combined effeft, which depends in part 

 on the repulfive force which their integral moleculae have 

 received from caloric, and in part from the attraftive force 

 of thefe moleculae." He then applies elegant formulae of 

 calculation to thefe phenomena. 



Soquet has made experiments, which feem contrary to thofe 

 of Count Rumford, refpefting the non-conduftilpility of ca- 

 loric by fluids. " I have feen," fays he, " at Venice a piece 

 of glafs, in a fi:ate of incandefcence, immerfed into a pail of 

 water without the latter being reduced to a fl:ate of vapour; 

 but, having plunged my naked arm into the water, I found 

 it exceedingly hot. I then approached my hand gently be- 

 low the mafs of glafs, and fenfibly felt iis heat." Fie admits, 

 however, that fluids in general are not good condufclors of 

 I i a caloric. 



