ON FLUIDS AS CONDUCTORS OF HEAT. 135 



on it, as gently as poffible, to about tlie quantity of 74 ounces; Dstail of Count 

 this water was about eight inches above the lurlace of the Ji'^."'^°''f '^J'^* 



t> periments on 



diik." heated fluids, 



*' The paper was then removed very gently, and after hav- 

 ing fuffered tlie water to remain a certain numbei: of minutes 

 in conta6l with the ice, it was poured off, and the jar with 

 the ice which it ftill contained inmiediately weiglied; its dif- 

 ference from the primitive weight eftabliftied the quantity of 

 ice which had melted while tlie hot water remained above 

 it." 



Having obferved that the motion occafioned by pouring on 

 the hot water produced an effedt which was confiderable, and 

 foreign to the communication of heat, the author fucceffively 

 devifed feveral modes of diminifhing it. " He introduced the 

 hot water through a wooden tube, clofed at the bottom and 

 pierced laterally with feveral fmall holes, through which th6 

 water iffued upon a wooden dilk, alfo pierced like a fieve, and 

 floating on the water as it rofe in the veflTei. This dilk was re- 

 moved as foon as the water was poured in, and the veflel wais 

 covered with a wooden lid, in the centre of which was fuf- 

 pended a thermometer; finally, by previoufly covering the ice 

 with a (Iratum of cold water, about half an inch in thicknefs, 

 in which the perforated wooden diflc floated, the author fuc- 

 ceeded in greatly diminifliing the irregularity of the refulls." 



Befides, thefe precautions, the author feparated from his 

 refults the quantity of ice, which liquefied at the firfl inftant, 

 and which exceeded that which melted in the fucceeding fpaces 

 of time; in thefe diflTerent experiments, while that part of the 

 cylinder which contained the ice was kept conftantly at the 

 temperature of melting ice, the upper part was left incontaiSt 

 with the farrounding air, or furrounded with a bad condu<^ting 

 fubftance, or plunged into the mixture of water and ice: the 

 water poured on the ice received different temperatures. 1 

 make three divifions of the refults of all the experiments: 1ft, 

 Water which was only about four degrees above zero, melted 

 a little more ice in the fame fpace of time than boiling water: 

 2d. When the upper part of the cylinder was wrapped in a bad 

 conducing fubftance, the hot water melted more ice than when 

 it was in contact with the air: 3d. When the upper part of 

 the cylinder was plunged into the mixture of ice and water, 

 more ice was melted than when it was left in contact with the 

 atmolphere at 61? Fahrenheit's thermoraeter. 



To 



