AEROSTATICS. 233 



stantly melted, and the temperature of the whole 

 is found to be exactly 32. 



In this experiment, 140 degrees of heat have en- 

 tirely disappeared ; and the same happens what- 

 ever be the temperature of the water. Dr BLACK 

 was the first who made this experiment; and as 

 he found that the heat which had thus ceased to 

 affect the thermometer, was not lost, but became 

 sensible again on the congelation of the water, 

 he said that it had become latent, a term well 

 adapted to express the fact, without any allusion to 

 theory. 



826. From the combination of this experiment 

 with the formula in the last article, the beginning 

 of the scale of heat, or the point to which the mer- 

 cury in the thermometer would sink, if it were to 

 lose all its heat, may be determined ; and it will be 

 found, that if c is the capacity of water for heat, 

 c' of ice, and x the number of degrees by which 

 the beginning of the scale of heat is below the 



32c'+11 

 beginning of FAHRENHEIT s, CD =2 t 



~* C/ 



For, according to this notation, the total heat in 

 ice, of the temperature 3, is c' (32 4- <r) ; and 

 the heat in water of the temperature 176, is 

 c (176 + x) ; therefore the total heat, when they 

 are mixed, and the whole reduced to water, is 

 % c (32 + x). This last expression must be equal 



to 



