372 KEPOET— 1886. 



point of view, te neglected. The same can be said of any other solvent of very- 

 small ' active mass.' We are, then, in a position to assert the following pro- 

 position : — 



(34) More active acids displace less active acids from solution of their 



salts. 



This is the proposition which, valid for bases also, is foimd in § 5 to agree so- 

 well with reality. 



[To avoid the appearance of verbal obviousness in this statement, we can 

 remember that by ' more active ' the author means ' having a higher molecular 

 conducti^'ity.'] 



Case 2. Both electrolytes are salts very little decomposable by water. In this 

 case the water may of course be neglected, and q/3 nearly equals /3y ; so from 

 equation (2a) one perceives that x has a magnitude comparable to w — a.- or 1—x. 

 Thus a sensible partition of the bases among the acids will be effected. 



(35) If txDO salts, of which the four ions are different, are dissolved in ivater 



{or any other solvent), the two other salts possible 2oill form to such 

 degree that their amounts will he comparable to the amounts of the 

 primitive salts, when the four salts are not notably decomposed by the 

 solvent. 



This proposition, very often verified, expresses a general opinion accepted by 

 chemists. (<S'ee Berthelot.) 



Case 3. If, on the other hand, one of the four possible salts — say that with the 

 coefficient /3 — is to a high degree decomposable by the solvent (which is the case 

 if it be composed of a feeble acid and a feeble base), but none of the others, 

 an equilibrium will establish itself between this salt, its acid, its base, and the 



solvent, in such a way that only a certain fraction, - , remains as a salt in the 



P 

 system, of the quantity which would be found if the salt were not decomposed, 

 (2a) takes the form — 



{n-x)(l-x)a8= - 8y. 

 P 

 So X will increase with p, that is to say — 



(36) In solutions of tico salts, of which one is composed of strong acid 

 and feeble base, the other of feeble acid and strong base, the strong acid 

 unites by preference with the strong base, leaving the feeble base to the 

 feeble acid. This latter salt is naturally in great part decomposed by 



the solvent. 



This proposition has been experimentally proved by M. Berthelot (p. 712). 



Case 4. If two feeble acids have the same base, M. Berthelot believes he has 

 proved that a sensible partition is effected. According to what has just been said, 

 this ought to be a special case of 1, so that if the acids are almost equally strong 

 a partition occurs ; if, on the other hand, one of them is much the stronger, it seizes 

 on a portion of base incomparably the larger. The work of M. Berthelot gives 

 examples of both cases. Thus a partition occurs between hydrocyanic and boracic 

 acids ; while the phenol of the phenate of potassium is displaced by boracic acid. 



§ 10. Influence of acid salts. 



Salts called ' acid ' are in general completely decomposed by water in sufficient 

 quantity. According to M. Hittorf, acid phosphates are exceptions. Nevertheless, 

 we have proved that NaH„POjj is partly decomposed by great dilution (see 

 Part I. § 19). 



The ions of acid salts are on the one hand a metal, and on the other the rest 

 of the molecule. If, then, one mixes sulphuric acid vpith, say, sulphate of soda, 

 a portion of NaHSO^ is formed. But NaHS04 behaves as any other salt, i.e.,. 



