Chemical Affinity. 



201 



acids and for bases is accounted for by Ostwald by the hypo- 

 thesis that the change of physical properties brought about by 

 each substance entering into chemical combination is of constant 

 value, and is independent of any alteration caused by the entrance 

 into the compound of other substances. 



The volume-changes which accompany the action of mono- 

 basic acids upon the normal salts of the same acids are shown 

 to be very small. The volume-changes accompanying the 

 action of one monobasic acid upon the normal salt of another 

 acid are determined by Ostwald ; and by dividing the number 

 so obtained by the difference between the volume-changes 

 noticed on neutralizing the base by each acid separately (a 

 small correction being made for the action of the acid set free 

 in the reaction upon its own normal salt), numbers are ob- 

 tained representing the percentage amount of base taken up 

 by the added acid. These numbers are contained in the fol- 

 lowing Table, in which the first column contains the name of 

 the normal salt, and the second that of the free acid added. 

 One equivalent of free acid is always added to one equivalent 

 of normal salt. 



Table XI. 

 Division of Base between two Monobasic Acids. 





Potash. 



Soda. 



Am- 

 monia. 



Mean. 



Dichloracetate. Nitric acid 



77 

 74 

 (70 

 \73 

 8 

 92 

 97 

 43 

 25 

 21 

 19 

 54 

 56 

 78 

 43 



77 

 75 

 (71 

 171 

 9 

 92 

 96 

 46 

 23 

 21 

 19 

 52 

 51 

 80 

 44 



75 

 73 



{5 



n 



92 



97 

 48 

 23 

 19 

 18 

 53 

 53 

 79 

 45 



76 



74 



71 



9 

 92 

 97 

 46 

 24 

 20 

 19 

 53 

 53 

 79 

 44 



Do. Hydrochloric acid ... 

 Do. Trichloracetic acid .. . 

 Do. Lactic acid 



Monoehloracetate. Trichloracetic acid 



Formate. Trichloracetic acid . . . 



Do. Lactic acid 



Do. Acetic acid 



Do. Butyric acid 



Do. Isobutyric acid 



Butyrate. Acetic acid 



Isobufyrate. Acetic acid 



Propionate. Formic acid 



Glycollate. Formic acid 





A similar table is given by Ostwald containing his results 

 obtained by the chemico-optical method ; the general results 

 agree very well with those of Table XI. 



Taking the affinity of nitric acid as 100, and that of hvdro- 



