\g() ON THE NATCTJIE OF HEAT.' 



to the other veflel clean and bright, and alfo filled with the 

 fame fluid at the fame heat, was found to be much more calo- 

 rific. The bubble which moved from the coated body, did 

 ■not return to its ftation until this body was removed to a dif- 

 tance five times as great as that of the other. Whence our 

 author concludes, that it emitted twenty-five times the quan- 

 tity of calorific rays. 

 Exp.aa. Simi- Exp. 22. The velfels ufed in the lafl: experiment were 

 ice-coM water. ^'"P^"^^ ^"^ refilled with ice and water. They were then 

 The gold -beat- prefented at equal dillances from the refpeftive balls ; and the 



duce?more°cold^^^^ ^^ ^^^ ^^^^ ^'^^^^^ ^^^ covered with gold-beater's Ikin, 

 by radiation. was much more confiderable in producing cold. r 



The radiation of cold bodies appearing to the Count thus to 

 be proved beyond all doubt, he was defirous of afcertaining 

 whether the frigorific rays pofiefs an equal power of aff'efling 

 the temperature of bodies as the calorific rays do ; the tem- 

 peratures of the radiant bodies being at the fame difiance each 

 way from the body to be atled upon. 

 £xp. aj. A hot Exp. 23. With this intention, one of the vefl!els filled with 

 Ttirm'nf PO""^e^ ^ce and water, was prefented to a ball of the infiru- 

 from the com- ment, and the other veflel filled with water at 1 J 2°, was 



mon tejnpera- prefented at an equal dillance on the oppofite fide of the fame 



tUre, affedt the , ,, , ^ _ , , . ^ 



thcrmofcope ball ; the temperature ot the room and mltrument bejng 72 , 



equally. or 40° diftant from each of the temperatures of the veffels, 



and the other ball of the infi:rument being defended from all 



radiation by fcreens. The bubble remained motionlefs ; fa 



that the oppofite aftions were in fa6l equal. And when either 



veffel was drawn farther off', the efFe6l of that veflel became 



lefs, and the bubble moved ; that is to fay, towards the ball if 



the cold veflTel were ne^irefl:, or from the ball if the hotter ; 



' and thefe efleds were equal in quantity as well as in celerity 



of motion. 



Why the cool- The Count again repeats his conclufion from thefe expe- 



ingbyrarfiatioiiriinents lately exhibited to Profeifor Pidet, M. de Saufliire, 



has been lels no- jT.,r,,. ^ ,, ,., ,, 



t]cea. and M. benebier at Geneva, that the rays which generate cold 



are ju ft as real and juft as intenfe as thofe which generate 

 heat ; and he proceeds to account for this refult having been 

 overlooked, by obferving, that the degrees of cold we are able 

 to produce, are much lefs diftant trom the ufual temperature 

 than thofe of heat, which are within our power. Thus a can- 

 non ball, hvMtcd to i6J degrees, or 70 degrees above blood- 

 heat. 



