200 ON FLUIDS AS CONDUCTORS OF HEAT. 



panfion by Its this air only adheres by a true affinity, which probably reduces 



whichX'a^r '^^ dimenfions, or at leaft, oppofes its dilatation; and if the 



adheres to it. water can drive it off, it is only becaufe it combines with 



thefe fubftances, and adheres to their furface by its affinity ; 



fo that the air will then experience the fame effisdl from the 



adlion of the affinity of the bodies to which it is adherent, 



as is produced on its elaftic efTort, by the fpace within which 



it is confined, and in which it receives a higher temperature 



without having the power to dilate. 



So that elaftic Thus the elaftic fluids wiiich dilate much more by a fimilar 



fluids being more ^.^ange of temperature than liquids and folids, mull have the 

 alterable in their . v V , c ■ r, ■ •• 



volume, are correjponduig faculty or entering more eahly mto combma- 

 alfornoredifpofed tion with caloric : they ofFer but Itttle refiftance to compref- 

 jieat. fion ; they heat by the redu6lion of their volume; and they 



cool when they dilate : do not thefe efFefls announce a great 

 difpofition to combine with caloric, or to abandon it, and to 

 receive different degrees of faturation from it? and never- 

 thelefs, according to the opinion of Rumford, there muil be 

 an infurmountable barrier between the moft diftant tempera- 

 tures, of the different particles of a gas, when the particles 

 do not meet with a folid body. 

 The fame doc- It is poffible, that liquid fubfiances may be much better 

 trine applied to calculated to conduct heat than when they are in a folid iiate ; 

 Sudderaccumu- 1'^6 properties of the reciprocal affinity which produces cohe- 

 lation or abforp- fion, feem to point this out : for (ince this affinity oppofes the 

 tionbyitsfufionj jj,^ ; j^ ^jjj ^g-^^. ^^^ obftacle to the combination of the - 

 It condudts ' 



better than ice, caloric : this refiflance to its introdu6tion is alfo proved by the ■ 



*^^' quick accumulation which is made of it, as foon as the force ! 



of ccliclion is deflroyed, fo that it is oppofed to the com- 

 bination of caloric, as well as to that of other fubfiances; in 

 fad, water feems to take the common temperature more 

 eafily, independent of the locomotion of its particles, than 

 ice, vfhich is a very bad condu^^or, and it is perhaps from 

 tills difference, that ice, and all the folids which pafs to the 

 liquid flate, liquefy at the furface, infiead of taking the 

 common temperature. 



I only offer thefe laft explanations as conjectures, which may 

 jnvile to experimental enquiries on a fubjed which is not 

 indifferent to chemical theory. 



A Mtmoir 



