with Observations on the Analysis of Salt-lmies. 23 



rates most powerfully, in relation to the fluid which is the me- 

 dium of action, are combined together. So much is this the 

 case, that, as Bertliollet has justly remarked, we may, from a 

 knowledge of the solubility of the compounds which substances 

 form, predict what combinations will be established when they 

 act on each other ; those ahvavs comi)ining which form the least 

 soluble compounds. .*>o far the influence of this has been illus- 

 trated by this able chemist. But it appears to me to admit 

 of further extension, so as to afford a solution of the present 

 question. 



If the force of cohesion can so far modify chemical attraction, 

 as to establish among compound salts dissolved in any medium, 

 those combinations whence the least soluble compounds are 

 formed, we are entitled, 1 conceive, to conclude, that the re- 

 verse of this force, that is, the power of a solvent, may produce 

 the opposite effect, or cause the reverse of these combinations to 

 be established. Suppose muriate of magnesia and sulphate o 

 soda to be dissolved in water, and the solution to be concen- 

 trated by evaporation, the combinations of sulphate of magnesia 

 and muriate of soda being on the whole less soluble in water, 

 this circumstance of inferior solubility, or the force of cohesion 

 thus operating, may determine the formation of these, and, ac- 

 cordingly, their formation is found by experiment to take place. 

 But suppose sulphate of soda and muriate of magnesia to be dis- 

 solved by the aid of heat in alcohol so far diluted as to effect 

 their solution, then those combinations will not be established 

 which existed in the watery solution, because, on the whole, sul- 

 phate of magnesia, and muriate of soda, are less soluble in alco- 

 hol, even in this diluted state, than sulphate of soda and muriate 

 of magnesia. These latter compounds will, therefore, remain 

 undecomposed.- But further, this may give rise, or, rather, must- 

 give rise, in conformity to the principle above stated, to the re- 

 verse effect ; so that, suppose sulphate of magnesia and muriate 

 of soda to be submitted to the action of this diluted alcohol, aided 

 by heat, the solvent power considered, in relation to the reverse 

 combinations, may cause the change in the state of these com- 

 pounds, and their transition into muriate of magnesia and sul- 

 phate of soda. 



In the analysis of sea-water, then, by the first or the methods 

 above described, the evaporation mav either, if sulphate of mag- 

 nesia and muriate of soda are the original ingredients, afford 

 them undecomposed in the solid state; or, if muriate of mag- 

 nesia and sulphate of soda are the ingredients, it may cause, by 

 the influence of the force of cohesion, the formation of sulphate 

 of magnesia and muriate of soda. But when the solid mass is 

 submitted to the action of alcohol, its operation, as a solvent, 



B 4 niay? 



