354 CONTRACTION OT WATER BY HEAT. 



become poffefled of feveral feries, well devifed, and, in 

 my opinion, of thctrifulves conclufive, it may yet be worth 

 •while to ftate Jthe.tenor and refult of them, by which the value 

 of their *tetlimon:y an favour of the conducting- power of liquids 

 niay be eftimated. 

 Experiments to ■ -The experiments were:of two defcriptiotts. 



«n W defcend C in The oncfet > °' f the fame nature » earl y Wi ^ thofe of Count 



fluids: Rmnford, was deiigned to examine, Whether heat, when 



applied to the • for face, can defcend.in.a fluid ; and the other 



ioidifcover, Whether, on the mixture of different portions of 



fluid at different temperatures, an interchange of caloric takes 



frlace between the. particles; — Water, oil and mercury, having 



been the fubjecls of the Count's experiments, were employed 



for the firft fet. 



To water (and to To explore the conducting power of water and oil, the 



communlcaLT 3 a PP aralus which l ufed confided of two veftels <of tinned 



from the bottom iron, both cylindrical, and the one fomewhat larger than the 



of a metallic vef-Qtj^^ fhe larger had a diameter of eleven inches, and into 



*el (in contact . .^ -..„», . , ,. ~ . . 



with the furfacs 11 " were Poured the fubjects of the trial, to different depths on 



or the fluid, different occaiions. The, fmaller was ten and a half inches 

 boiling water Y m diameter. By three liooks it was fufpended within the 

 •within. Jarger pan, in i'uch a manner, that the bottom of it exactly 



reached and. came in contact with -the furface of the fluid. 

 This fmaller veffel became the fource of the heat, by being 

 •filled with boiling hot water. The water, was changed fre- 

 quently, care being taken to avoid, by the ufe of a fyphon, 

 all agitation and difturbance. 

 Thfe hot veiTal In experiments of this nature, the difficulty is to prevent 

 thi n whic°h C con- lue convince of caloric by the fides of the veflel. I at- 

 tained the fluid tempted, and, I think, I fucceeded, in overcoming this diffi- 

 xinderexpcn- ca \iy y D y encircling the larger velfel, as a height exactly cor- 

 comaining venel-refponding with that of Ihe.furface of the fluid within, with 

 was kept cold a g U t t er or channefabouf half an inch in depth; and by caufing 

 face of theflui"d,a ft ream of cold water to flow conftantly through a fyphon into 



and therefore this gutter, while from the cppofite fide it ran off by a final I 

 Aid not carry any f 

 heat downwards. l P ouU 



The water was feveral degrees colder than the fubject of the 



experiment; and keeping cool the portion of the veflel with 



which it was in contact, it intercepted the heat that would 



othefwife have travelled by this route to the bottom. 



Mercury was For mercury I had recourfe to-veflels of glafs. . 



tried in g'afs \i\ 



%eflels. 



