OF SEA-WATER. 215 



Carbonate of Magnesia, 1.7 



2.8 



4.5 4.5 



The two last ingredients might be accidental products, from 

 the decomposition of muriate of magnesia and of lime. Mu- 

 riate of magnesia is decomposed by heat ; a portion of its acid 

 is expelled ; and the magnesia separated in consequence of this, 

 will absorb carbonic acid, from the current of warm air applied 

 during the evaporation, or from the carbonic acid gas which the 

 sea- water itself contains, and which is not immediately expell- 

 ed by heat. The small portion of carbonate of lime might be 

 produced in a similar manner, or from the action of the carbo- 

 nate of magnesia on muriate or sulphate of lime. I according- 

 ly found, in a subsequent analysis, that on adding muriate of 

 barytes to sea-water, no carbonate but only sulphate of barytes 

 is precipitated, which proves that these conclusions are just. 

 For the small portion, therefore, of carbonate of magnesia, the 

 equivalent portion of muriate of magnesia, 4.2, raising it to 

 103.6, is to be substituted. If the lime which afforded the car- 

 bonate existed in the state of sulphate, then the equivalent por- 

 tion of this 3.4 is to be added to the sulphate actually obtain- 

 ed, making it 28.4. If it existed in the state of muriate of 

 lime, it still would, but for this change, have been converted in 

 the progress of the evaporation into sulphate of lime; the same 

 substitution, therefore, is in this view equally to be made. 

 With these corrections, and reducing the proportions to a pint, 

 the ingredients and their quantities will be as follow : 



Muriate of Soda, - 182.1 grains. 



Muriate of Magnesia, - 25.9 



Sulphate of Soda, - 7.5 



Sulphate of Magnesia, - 5.9 



Sulphate of Lime, - Id 



228.5 



The 



