OF SEA-WATEll. 227 



The question now remains for consideration, What is the real 

 composition of sea-water ? How far are the salts obtained in 

 either mode of analysis, those which exist originally in solu- 

 tion ? This question is evidently to be considered under the 

 same point of view as that which I have illustrated in a former 

 paper, with regard to the change in the state of combination, 

 which may be produced in the saline compounds existing in 

 mineral waters, by the analytic operations to which they are 

 subjected. We have no strict evidence that the binary com- 

 pounds which are obtained are those which existed in solution, 

 admitting even the principle that binary combinations exist. 

 On the contrary, there is every probability, that the substan- 

 ces obtained are often products of the operation, arising from 

 changes of combination which it established. And this is 

 even placed in a more striking point of view in the present 

 case, as the ingredients obtained are actually different, when 

 different methods of analysis are employed. It is, therefore, 

 necessary to inquire farther what the real composition is. 



With regard to the sulphate of lime, which is the first sub- 

 stance separated by the evaporation, the general views I have 

 already stated, give every probability to the conclusion, that 

 it is a product of the operation formed by the action of sul- 

 phate of soda or of magnesia during the evaporation, on mu- 

 riate of lime ; that this last salt, therefore, is an ingredient in 

 sea-water ; the proportion of it being the quantity equivalent 

 to that of the sulphate of lime which the analysis affords. 



The small portions of carbonates of magnesia and lime 

 which are obtained in the evaporation, I have already stated, 

 are evidently accidental products from the decomposition of 

 muriate of magnesia and muriate or sulphate of lime. 



The large quantity of muriate of soda leaves no doubt, if bi- 

 nary compounds at all exist in a state of solution, that it is the 



F f 2 chief 



