ON FLUIDS. ]35 



Betides (hofe mod ingenious experiments devifed by Murray, p r° of " s that 

 , , r r i . a- f i- i • fluids are proper 



we have other proofs of the conducting power or lujinds in con 4 U &ors. 



feveral well known facts. 



]Ji. If the non-condu&ing power of liquids have any mean- i. They take a 

 ing, it mud fignify that their particles are incapable of com- c ™"^ m " 

 municating to each other the temperature they have acquired mixing, 

 by phy ileal contact wilii fome other body, whofe temperature 

 was elevated. If this were true, how (hall we account for 

 the mean temperature produced by mixing equal quantities 

 of hot and cold water? Rum ford, if I recollect aright, has 

 endeavoured to obviate this objection to his hypothecs by 

 fuppoiing, that it is only an intimate mixture of hot and 

 coid particles which takes place in fuch cafes. If this were 

 true, we fhould expect, from the rapid motion he fuppofes 

 the currents to have in liquids that are heated, that they 

 would foon feparate into warmer and colder frrata, from the 

 difference in their fpecific gravities : This however is not the 

 cafe: The whole acquires a uniform temperature. 



2d. When mercury and water at different temperatures 2. More parti- 

 are mixed, an interchange of caloric takes place. From the cu f r J o ™ at " 

 o * and mercury. 



very great difference of their fpecific gravities we cannot 



fuppofe that every particle of the one has been in contact 



with every particle of the other; yet they foon acquire a 



common temperature, which though not a mean, has always 



a conftant relation to the temperature of the two fluids before 



mixture. Does not this indicate a confjderable conducting 



power in thofe liquids ? Indeed, I cannot conceive that any 



interchange of temperature could take place in fuch cafes, if 



the particles of the liquids were incapable of communicating 



•their caloric to the next particles. 



'3rd. The beautiful experiment devifed by Rumford, in 3. The veflel is 



which water, in a glafs tube, was made to boil over a cake t0 ° bad a con " 



ii ' 1 • . r 1 . • , , duclortoac- 



or :ce, by the application of a heated body to the upper part count for the 



of the containing tube, without, for a very long time, affecting e fl" e<Ss ur g ed 

 „, . . r Z~ . r .. . ,, ,. . , . . , , ? againft the doc- 



<the ice, is a iurhcient proof of the ilownels with which glafs tr ; ne f q # r. 

 -tranfmils caloric, and clearly indicates that the fides of the 

 vetfel in feveral of the experiments of the above-mentioned 

 philofophers, could not be the fole conducting medium. 



4fth. The fixteenth experiment in Rumford's feventh effay, 4* H °t u 'ater 

 affords another argument againft his opinion. He poured doeTnVTraTfe 

 • boiling water on a ilratum of cold water, which retted -on a its temperature 



Cake by currents. 



