J3^ ON FLUIDS AS CONDUCTORS OF HEAT, 



XX. 



Ohfervations upon the Dodrine of Count Rupiford refpe6iing the 

 want of dired conduSiing. Power in Fluids with regard to 

 HcHt. %CiT. Berthollet.* 



Thedoftrincof ^OUNT RUMFORD has publiQied feveral memoirs, by 

 Count Rumford ^^.]^\^\-^ 1,^ \-^^^ endeavoured (o prove that liquids and elaftic 

 on the non-con- -.i, ■ r- 



dueling property fluids are not conduciors or heat, and that they only tranlmit 

 of fluids defeiveS(^,alo[-ic by means of the contad with folid bodies, which is 

 examination, • . ,i • c ^ • . ^i • l ij 



owing to the motion of their parts: as this property would 



make a difference between the ftates of a fubftance much 



greater than there is occafion to fuppofe in the explanation of 



the other phenoniena; as, befides, this celebrated philofopher 



has fixed the attention on an object which had been negleded, 



and has drawn applications from it, beneficial in the arts, and 



in the ufes of life, I think it proper to offer fome doubts on the 



principles vvhich he has deduced from his ohfervations: 1 fliall, 



in the firft place^ examine whether the fads on which he relies, 



cannot admit of a natural explanation from the properties 



which I have already analyfed, or whether it will be neceflary 



to have recourfe to particular properties. But I fhal! attend 



only to the confiderations which may ferve to elucidate this 



difcuffion, without introducing the details it would require, if 



I were to examine it more fully. 



Detail of Count The experiments which the author made were performed 



Rumtord's ex- yyijj^ an apparatus, of which it will be proper to infert a de- 



periments on . . . i- i • i i 7 • ,• • i 



heated fluids. Icripti-on. " He employed a cylindrical glais jar or 4.7 inches 



in diameter,, and 13.8 in height; he put a known quantity of 

 water (about two pounds) into the jar, which was intended 

 to form a cake of ice at the bottom of the vedel. For this 

 piirpofe, the jar with the water was put into a frigorific mixr 

 ture of fait and ice, the adion of which was not long in con- 

 verting the water into a (olid dilk adhering to the bottom and 

 fides of the jar; the jar was then removed, and plunged into a. 

 mixture of ice and water, to the level of the interior cake, 

 )vhich gave it the temperature of melting ice, or of the zero 

 of the common thermometer. Then, alter having covered the 

 furface of the ice with a dilk of paper,f hot wa^er was poured 



* From his EfTai de Statique Chemique, 

 t Bibl. Biit. 



m 



