420 M. J. Thomseir's Thermo -chemical Researches. 



W e see that in every case the agreement between calculation 

 and observation is as satisfactory as the degree of accuracy ob- 

 tained in the measurement of thermic effects will admit of. 



The value denoted by k in the formulae of Guldberg is no other 

 than the ratio of the avidities of the two acids which act simul- 

 taneously. If a and a 1 represent the avidities of the two acids A 

 and A' for the base B, the energy of the decomposition of BA 



a 

 by A' is k = — , and the energy of the inverse reaction of A on 



If the two acids have the same avidity k — 1, then 



a/3 — 78 



oc = 



and if 7 = 8 = 0, 



« + /3 + y+s ' 





4-/3 



we then recur to the formula of Berthollet, which is thus con- 

 firmed only in the particular case in which acids of which the avi- 

 dities are equal are compared. 



The author terminates this memoir by the following summary. 



1. When two acids act simultaneously in an aqueous solution 

 on a base of which the quantity is insufficient to neutralize them, 

 that base is divided between them in such a manner that they 

 form two salts, and a part of the two acids remains free. 



2. Hence it follows that when on a salt an acid reacts of which 

 the heat of neutralization is greater than that of the acid con- 

 tained in the salt, the reaction is accompanied by a disengage- 

 ment of heat ; in the inverse case there is, on the contrary, an 

 absorption of heat. 



3. The division of the base between two acids is not effected 

 according to the law of Berthollet — that is to say, proportionally 

 to the number of equivalents of the two acids. 



4. The division does not take place in the ratio of the affinities 

 of the base for the two acids, if we take as a measure of these 

 affinities their heats of neutralization. 



5. The force with which the acids tend to be neutralized is 

 what I call avidity. 



6. When an equivalent of a base is in the presence of two acids 

 in an aqueous solution, the amount of each of these acids in the 

 mixture being one equivalent, the base divides itself between 

 them according to the ratio of the avidities of the two acids. 



7. If the acids are in a different proportion, the base divides 



