224 AN ANALYSIS 



that the reverse 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 magne- 

 sia and sulphate of soda to be dissolved in water, and the so- 

 lution to be concentrated 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 for- 

 mation of these, and, accordingly, their formation is found by 

 experiment to take place. But suppose sulphate of soda and 

 muriate of magnesia to be dissolved by the aid of heat in al- 

 cohol so far diluted as to effect their solution, then those com- 

 binations will not be established which existed in the watery 

 solution, because, on the whole, sulphate of magnesia, and mu- 

 riate of soda, are less soluble in alcohol, even in this diluted 

 state, than sulphate of soda and muriate of magnesia. These 

 latter compounds will, therefore, remain undecomposed. But 

 farther, this may give rise, or, rather, must give rise, in confor- 

 mity to the principle above stated, to the reverse 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 com- 

 binations, 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 of the me- 

 thods above described, the evaporation may either, if sulphate 

 of magnesia and muriate of soda are the original ingredients, 

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

 magnesia 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 



