COHESION OF SOLUTIONS. 237 



Dr. Lardner states, that the solution of a salt 

 in water diminishes the cohesive force of the liquid, 

 and therefore lowers its freezing point. (Trea- 

 tise on Heat, p. 194.) 



The fact however is just the reverse, for a 

 saturated solution of chloride of calcium in water 

 requires 42 more caloric to overcome its cohe- 

 sion than pure water that is, it requires a tem- 

 perature of 264 F. to make it boil. In other 

 words, the particles of water, which are held 

 in a state of chemical union with the salt by ca- 

 loric, have a stronger attraction for the particles 

 of chloride of calcium, than for each other ; 

 therefore cannot be separated and driven off in 

 the form of vapour without an augmentation of 

 temperature. 



From the preceding facts and observations we 

 are brought to the general conclusion, that the 

 deliquescence of salts, the production of cold 



that when dissolved in hot water, and tightly corked up in a 

 phial, it cools down without crystallizing, if kept perfectly still. 

 But if shaken, a portion of the caloric which held it in a state 

 of combination with the water is disengaged, when the phial 

 becomes warm, and the solution crystallizes. If the cork be 

 withdrawn, the same effect is produced, owing to the mechanical 

 pressure of the atmosphere, which forces out of the solution a 

 portion of its caloric. By inserting into it a piece of ice, or any 

 salt that has an affinity for caloric, crystallization is produced 

 for the same reason that all other fluids are congealed by the 

 abstraction of their caloric. It has been said that a film of oil 

 retards the crystallization, which is no doubt the fact, because a 

 bad conductor of caloric, and therefore prevents its ready escape. 



