240 THEORY OF FREEZING MIXTURES. 



is 28 below the freezing point of water and if 

 the same quantity of carbonate of soda be added, 

 the temperature is reduced 7, or 39 below 

 32. If then such salts can abstract caloric from 

 water at 4, and even below zero, it follows a 

 fortiori, that they can take it from snow at 32. 



Dr. Turner observes, that when salt and snow 

 are mixed, the salt causes the snow to melt by 

 reason of its affinity for water. But if the snow 

 and salt be cooled down 9 there is no attrac- 

 tion between them, and therefore no solution 

 nor reduction of temperature. The truth is, that 

 all freezing mixtures are dissolved by caloric 

 as certainly as that snow is dissolved by boiling 

 water ; for the simple and sufficient reason, that 

 caloric is indispensable to all fluidity, without 

 which there can be no chemical combination. 

 " Corpora non agunt, nisi sint soluta" When snow 

 is dissolved in the strong acids, there is a rapid 

 transition of caloric from the acids to the snow, 

 by which they are chemically combined, with 

 a reduction of temperature, as in the solutions 

 of ice or salts in water. If 8 parts of snow be 

 dissolved in 5 of muriatic acid, there is a re- 

 duction of temperature from 32 to 27: or 

 if 7 parts of snow be dissolved in 4 parts of 

 diluted nitric acid, the mixture falls 30. The 

 same effects are produced by mixing pulve- 

 rized salts with the strong acids. 



After having demonstrated that caloric is the 



