22 An Inquiry concerning the Weight ascribed to Heat. 



I afterwards contrived an apparatus for making the 

 experiment in a different and more unexceptionable 

 manner. I provided three hollow globes of brass, very 

 thin, and one larger than the other, and which being 

 made to open in the middle, like a tobacco-box, could 

 be placed one within another. In the centre globe I 

 intended to place a solid bullet of pure gold, red-hot. 

 Between the centre globe and that next it, I proposed 

 to leave a space equal to the diameter of the heated 

 bullet, filled with air ; and the space between the sec- 

 ond globe and the third I meant to have filled with 

 pounded ice ; and I proposed to have made the ex- 

 periment at a time when the heat of the atmosphere 

 should be just equal to that of freezing water; and in 

 this manner I conceived that I should be able to avoid 

 the currents in the air, whose effects I had found so 

 distressing in my former experiments. But when I 

 considered that the whole of the heat contained by the 

 red-hot bullet would not be sufficient to thaw one half 

 of the ice which surrounded it, and that, when the bul- 

 let should be cooled to the temperature of the ice, the 

 whole mass of metal, of ice, and of water, would still 

 remain at the point of freezing ; and, moreover, that 

 weighing the water produced by the ice would, in fact, be 

 weighing the heat which before existed in the red-hot 

 bullet, it first occurred to me that the point in question 

 might much more readily be determined by simply 

 weighing a quantity of ice at the temperature of freezing, 

 and weighing the same again when changed into water. 



I therefore left my apparatus unfinished, and turned 

 my whole attention to the experiments of which an 

 account has been given in the former part of this paper. 



[This paper is printed from Rumford's Philosophical Papers, 

 pp. 366-383.] 



