125 ON FLUIDS AS CONDUCTOR* OF HEAT. 



Explanation. To explain thefe obfervations, the properties which we have 



I More heat i-ecognized in liquid fubftances, and in elaftic flnirls, and from 

 will b-; commu- t> 'n ' 



located the great, which we have inferred the changes which are efFefted in their 

 er the difference different flates of combinations, muft be applied to the pheno- 



ef terrperaturi. ur J u r. r i 



». Locomotion Hiena ODlerved by Rumford. 



incieafes this We have feen, Ift. that the liquid particles enter fo much 



effedl in fluids, , . ,, . , . • , 



and ought to be ^he more rapidly into combination as" they were at a greater 



ftparately con- diftance from faturation, becaufe then the force which folicits 

 kcomotiondoes^^'^®^^^"''^'^^" '^ greateft ; fo that the effefts which depend on 

 not follow the the communication of the temperature muft be very weak, 

 tcmpe'raturc! ^^®" ^^^ differences between them are but fmall. 



2d. Locomotion, which ferves to bring particles together 

 which are at a greater diftance from faturation, accelerates the 

 effedl of the mutual aftionby which its equilibrium iseftablifh- 

 ed, fo that it is neceftary to feparate the effed which depends 

 on this caufe from that which is owing to immediate commu- 

 nication. 



3d. Water and fome other fubftances acquire a greater fpe- 

 cific levity on approaching the term of congelation; whence 

 it follows that the locomotion produced by the variations of tem- 

 perature in other circumftances will be fubje6l to modifications, 

 which muft be allowed for when water and the other liquids 

 which poftefs this property, approach the term of congelation. 

 To apply thefe properties, we muft alfo take into confider- 

 atlon the direftionin which the heat is communicated; for the 

 combination of effefls will be different accordingly as it is ap- 

 plied to the inferior or fuperior part of a liquid. 

 Locomotion is In order that a ready motion may be eftabliftied between the 



^ff^tcTofVem. particles which are at the bottom of the veffel, and thofe at the 

 feratureU Jmall. furface, there muft be but little difference between their tem- 

 perature; the particles which are near the ice, and become 

 expanded, will then raife themfelves above thofe which have a 

 temperature barely greater; but if the temperature fliould 

 caufe a great difference between the fpecific gravities, this mo- 

 tion will be much more confined, fo that the ice will remain 

 furrounded with water of its own temperature, or which is 

 very little removed from it. It is evident, therefore, that that 

 part of the efftfl which depends on the motion will be much 

 lefs, when there is a great difference in the temperatures. 



The effea of But when this diftance in fad exifts, the efl'ecl produced bv 



the heat by a ,, . . ~ , , . , , , ,. "^ 



fluid will be the communication of the heat, independently of the motion, 

 4- . . will 



