22 -An Analysis of Sea-iuatcr ; 



As the relative quantities of these salts are tluis varied, and 

 are indeed nearly altogether dependent on the kind of analysis, 

 it is obvious that one or other of them must be an original in- 

 gredient, and the other must be a product of decomposition. 

 If sulphate of magnesia is the original ingredient ; then, when it 

 is not obtained, or is obtained only in very inferior quantity, 

 while sulphate of soda is procured in its place, it must be held 

 that it is decomjwsed ; and the only decomposition that can ac- 

 count for the.'-e results is, that from the mutual action of muriate 

 of soda and sn!j)liate of magnesia, by which, while jiortions of 

 them are removed, corresponding portions of sulphate of soda 

 and of muriate of magiiesia are formed. On the other Jiand, if 

 sulphate of soda is the original ingredient, then, when it is not 

 obtained, or is obtained only in small quantity, it must be held 

 that it is decomposed ; and the only decomposition of it that 

 can here take place, must be from the action of muriate of mag- 

 nesia, by whicli, while quantities of both these salts are removed, 

 corresponding quantities of sulphate of magnesia and muriate of 

 soda will be jjroduced. 



Of the two analyses, the one in which sulphate of soda prin- 

 cipally- is obtained, is that in which the solvent action of alcohol 

 is employed ; the other, in which there is the mere separation of 

 the salts bv evaporation and crystallization, is that which af- 

 fords scarcely any of it, but in place of it sulphate of magnesia. 

 IMovv, it is to be observed, that in both of these the preliminary 

 operation of evaporation to dryness is the same. Since sulphate 

 of soda, therefore, is not obtained by this operation, it is ob- 

 vious, that, even on the assumption of its being the original in- 

 gredient of sea-water, it must, in the progress of the evaporation, 

 be decomposed bv the muriate of magnesia, and converted into 

 the sulphate of magnesia ; and hence, in the subsequent solvent 

 action of the alcohol, Ov which it is obtained, it must be re- 

 formed. And, on the other hand, if sulphate of magnesia is the 

 primary ingredient, and is obtained as such by the evaporation, 

 it remains to be explained, how it is converted in the subsequent 

 .solution by the alcohol into sul])hate of soda. The whole ques- 

 tion, therefore, resolves itself into the nature of the action of the 

 alcohol, producing sulphate of soda ; and of this I perceive no 

 other solution than that which I have now to illustrate. 



The fact, however it is to be explained, or to be reconciled 

 with the doctrine of chemical attraction giving rise to combina- 

 tions or decompositions according to the strength with which it 

 is exerted, seems to be establislied by an induction too strict 

 and extensive to admit of doubt, that these results are often de- 

 termined by the force of cohesion, in such a manner, that in 

 principles acting on each other, those on which this force ope- 

 rates 



