%j^ Caloric in Liiquids and in Vapour, 



caloric. He then makes fome refearches refpedling the 

 caufe why the water is not reduced to vapour by incandef- 

 cent glafs, while it is by incandefcent iron. 



Piclet has given fonie very interefting obfervations on 

 elaftic fluids, and aqueous vapour in particular. It appears 

 that all fluids are indebted for their elaftic ftate to the matter 

 of fire, or caloric. Some preferve this elaftic ftate at every 

 temperature, and this is the cafe with aqueous vapour. The 

 author endeavoured to determine the quantity of caloric con- 

 tained in wai M- in a fl:ate of vapour at the temperature of 

 ebullition ; and experience proved that this aqueous vapour 

 ,had eight or nine times more caloric than the fame water in 

 a liquid ftate at the fame temperature. The following are 

 the means he employed to obtain this refult : 



Let M be one of the mafles, and T its temperature ; m the 



other mafs, and t its temperature; the temperature of the 



... , MT + mt 



mixture will be — -— . 



M + m 



This formula he applied to the following experiment : — 



He took a balloon, the water in which weighed fix ounces, 



and was at the temperature of 13°. He introduced into this 



water, for five minutes, the vapour of an eolipyle, and the 



temperature of the water rofe to 49°, that is to fay, was 



raifed 36°, and its weight was increafed 228 grains. He 



then endeavoured to dlfcover what calorific effect would be 



produced by 228 grains of boiling water on fix ounces or 



3456 grains of water at the temperature of 130° ; that is to 



fay, what would be the temperature of the mixture. 



T, 1 • u L f 111 ,3456x13 + 228x80 



Bv applvmo: the above formula he had -i^i -;- ^ 



J i^'^ J ^ 34^6 + 228 



= 17" 15' for the temperature of the mixture. Boiling water 



then did not produce but 4° ^y^ more heat in fix ounces of 



water at the temperature of 13°; while the fame quantity of 



water, in a Hate of vapour, at the temperature of 80°, raifed 



the heat 36°. The calorific effeft, therefore, of water in 



vapour is abom 8^ times greater than that of the fame water, 



boiling. But the volume of the vapour is about 1800 limes 



greater than that of boiling water. There is therefore 21:* 



times more fire in any given volume of boiling \vater than 



in 



