On the Boiling Points of Saturated Solutions. 9 1 



The quantities expressed in the second column were ascertained 

 by weighing out a portion of the boiling solution, and after expell- 

 ing its water by heat, taking the weight of the dry salt that 

 remained. In this manner it was expected that very soluble salts 

 would yield the greatest quantity of dry salt, and the highest boil- 

 ing points. But in many instances this is not the case, and 

 remarkably so with sulphate of soda, its solution-containing only 

 31.5 per cent, and elevating the boiling point of water but one 

 degree *. The elevation of temperature does not seem to depend 

 upon the quantity of salt present, or its solubility. Tartarate of 

 Potassa, a salt very deliquescent, 68 parts of which are contained 

 in 100 parts of the solution, boils at 234°, whilst Mur. Ammonia, a 

 salt unchanged by exposure to air, of which but 50 per cent, is 

 contained in its solution, boils at 236°, a solution containing ninety 

 per cent, of Rochelle salt boils at 240°, whilst one of Acetate of 

 Soda containing only 60 per cent, of the salt boils at 256°. Solu- 

 tions of Prussiate of Mercury and Bi-Tartarate of Potassa boil 

 precisely at the same temperature, but the former containing 35 

 per cent, of dry salt, the latter only 9.5. 



The boiling points of the following solutions have not been 

 accurately determined, on account of the great difficulty of making 

 saturated solutions, but the numbers are probably very nearly 

 correct. 

 Pure Soda . . . 420° Solution corroding the thermometer's 



bulb 

 Nitrate of Ammonia 360 



Nitrate of Copper 344 



Caustic Potash . 316 increasing rapidly by continuatioii of 

 heat. 



Oxalic Acid • . 234 increasing and subliming at 250 



A curious circumstance happens when a solution of Carb. Am- 

 monia is exposed to heat ; it seems to boil at 180°, and if the tem- 

 perature be increased the salt evaporates, and by the time the 

 water reaches its boiling point, it is perfectly free from all traces of 

 the substance. 



• In experiinentiDg with this substance the crystals of the salt were 

 liquefied by heat^ and boiled in their water of crystallization. 



