p'oduced hy dissolving Salts in Water. 41 



of which may be, that the bulb of the thermometer being at 

 the bottom of the vessel where the salt actually dissolved, 

 probably the temperature in that spot might have been 

 rather higher than at the surface of the liquid. 



The specific gravity of anhydrous carbonate of soda is 

 2-640. 



The specific gravity of a saturated solution of carbonate 

 ofsodaat80°is 1-2291. 



It is composed of water .... 1 000 

 Anhydrous salt 292-3 



1292-3 

 The mean specific gravity of such a mixture is 1*1647. 

 But the specific gravity of the solution is 1-2291. It is, 

 therefore, a good deal denser than the means. This will 

 explain in part the reason why the temperature is greater 

 than it ought to be from theory. 



2. 300 grains of crystallized sulphate of soda in powder, 

 were thrown into 1000 grains of water of the temperature 

 67°'5, and the liquid was stirred about with a thermometer 

 till the whole salt was dissolved. A longer time elapsed be- 

 fore the sulphate dissolved than was requisite for the solu- 

 tion of the carbonate of soda. The thermometer sunk to 

 45°-5 or 12°. 



300 grains of anhydrous sulphate of soda in fine powder, 

 were thrown into 1000 grains of water of the temperature 

 61°-5, the mixture was stirred about with a thermometer. 

 The temperature rose to 65°-5. or 4°. This temperature 

 continued unaltered for nearly half an hour, showing that 

 the salt was giving out heat during the whole of that time. 



The quantity of salt dissolved was 165*8 grains. The 

 quantity remaining solid was therefore 134*2 grains. 



The specific gravity of anhydrous sulphate of soda is 

 2-640. 



The specific gravity of a saturated solution of sulphate of 

 soda at 61°*5 is 1*1549. 



Now the mean specific gravity of a mixture of 1000 grains 

 water of 61°-5 and 165-8 grains of anhydrous sulphate of 

 soda is 1-0959. The solution, therefore, is a good deal 

 denser than the mean. 



3. 300 grains of crystallized sulphate of magnesia in 

 powder were thrown into 1000 grains of water of the tern- 



