ANNALS 



OF 



PHILOSOPHY, 



JANUARY, 1820. 



Article I. 



On the Solubility of the Salts in Water. By M. Gay-Lussac* 



One is astonished, on perusing the different chemical works 

 at the inaccuracy of our knowledge, respecting the solubility of 

 the salts. They satisfy themselves with the common observa- 

 tion that the salts are more soluble in hot than in cold water, and 

 with the solubiUty of a few of them at a temperature usually 

 very uncertain ; yet it is upon this property of salts that their 

 mutual decomposition, then- separation, and the different pro- 

 cesses for analyzing them depend. As a chemical process, the 

 solution of the salts deserves peculiar attention ; for though the 

 causes to which it is due are the same as those which produce 

 other combinations, yet their effects are not similar. It is to 

 be wished that this interesting part of chemistry, after remaining 

 so long in vague generalities, may at last enter the domain of 

 experiment, and that the solubility of each body may be deter- 

 mined not merely for a fixed temperature, but for variable 

 temperatures. In the natural sciences, and especially in che- 

 mistry, general conclusions ought to be the result of a minute 

 knowledge of particular facts, and should not precede that 

 knowledge. It is only after having acquired this knowledge 

 that we can be sure of the existence of a common type, and that 

 we can venture to state facts in a general manner. 



The solubility of a body in water depends upon two causes, 

 affinity and heat, or more exactly the affinity of a salt for water 

 varies with the temperature. Lavoisier, whose philosophic 



• Translated from th»Ann. de Chim. et de Plijs, xi. 296. 



Vol. XV. N" I. A 



