356 Mr. A. Williamson's Theory of JEtherification. 



is very great, it is found that the stronger acid and stronger 

 base remain almost entirely together, leaving the weaker ones 

 combined. This is well known in the case of a mixture of 

 sulphuric acid and borax, and is a confirmation of our funda- 

 mental assumption, that the greater the difference of proper- 

 ties, the more difficult is the alternate interchange of one mole- 

 cule for another. 



But suppose now that instead of sulphate of copper, we 

 mixed sulphate of silver with our hydrochloric acid in aqueous 

 solution, and that a similar division of the bases between the 

 acids established itself in the first moment, forming four com- 

 pounds, S0 4 H 2 , S0 4 Ag 2 , C1H, ClAg; it is clear that this 

 last-mentioned compound, being insoluble in water, must, on 

 its formation, separate out and remove from the circle of de- 

 compositions which solubility established. But of course the 

 three compounds remaining in solution continue the exchange 

 of their component parts, and give rise successively to new 

 portions of chloride of silver, until as much of that compound 

 is precipitated as the liquid contained equivalents of its com- 

 ponent parts, a very small quantity remaining in solution and 

 in the circle of decompositions. 



Such is the general process of chemical decomposition. 

 Of course a compound is removed as effectually from the circle 

 of decompositions by possessing the gaseous form under the 

 circumstances of the experiment, or even by being a liquid 

 insoluble in the menstruum. I believe this explanation coin- 

 cides in its second part with the one proposed many years ago 

 by Berthollet; but not making use of the atomic hypothesis, 

 upon which my explanation is based, that eminent philosopher 

 went no farther back than the division of the acids between 

 the bases on the mixture of salts, a fact which I have here 

 deduced from the motion of atoms. It is well known that the 

 general fact upon which Berthollet founded his view is denied 

 by some eminent chemists of the present day ; but I believe 

 the instances which they adduce are only apparent exceptions 

 to the law, and will on further examination be found to afford 

 additional confirmation of the truth of the great Savoysien's 

 conception, as I have shown in the case of boracic and sul- 

 phuric acids. 



In using the atomic theory, chemists have added to it of 

 late years an unsafe, and, as I think, an unwarrantable hy- 

 pothesis, namely that the atoms are in a state of rest. Now 

 this hypothesis I discard, and reason upon the broader basis 

 of atomic motion. 



