HI8T0BY OF THE ATOMIC THEORY. 137 



we have hitherto acquired of the method by which combina- 

 tions are formed. I can readily conceive that the point at 

 which water is saturated with a salt may change according to 

 the temperature, and that cold water may absorb more of the 

 gaseous acid ; the increase or diminution of the matter of 

 heat in the solvent changing the respective disposition, the 

 density, and perhaps the figure of the molecules, it is not 

 astonishing that the attractive force should be modified by 

 these changes ; that they should result in a contact more or 

 less perfect, and that the power of affinity should be able by 

 this means to protect from (the influence of) the law of gravi- 

 tation a greater quantity of matter, in the one case, than in 

 the other ; but we have nothing of this kind in the hypothesis 

 under consideration ; the circumstances are the same ; the 

 point of saturation cannot change, because it is the effect of 

 a cause which does not change. 



" To make this clear, let us ask what is saturation ? Every 

 chemist will say that he understands by it the condition in 

 which a compound is, when neither of its constituents can 

 receive or retain in combination a greater quantity of the 

 other. Such is the rational and necessary acceptation of the 

 word saturation, otherwise it becomes void of sense ; then to 

 suppose, preserving this acceptation, that a substance may 

 be saturated with different quantities of the same substance, is 

 really to affirm two contraries." 



" * * * * Now, when a new quantity of any of their 

 principles is added to one of these perfectly neutral salts, 

 there is nothing to prevent an attraction between them, and 

 even in a degree capable of producing solution, combination, 

 or affinity ; but it must be remarked that this affinity is not 

 that of an acid to a base, or a base to an acid, but of the 

 neutral compound, with the portion that was added; whence it 

 follows ; 1st, that it has no effect on the previous composition 

 which remains in its integrity, as if the neutral salt were super- 



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