202 On Chemical Affinity. 



chloric acid as 98*, the affinity of dichloracotic acid is 



24 26 



Y* x 100 = 32, or, starting from hydrochloric acid, ^-, x 98 = 34. 



In this manner the following Table is framed : — 



Table XII. 

 Relative Affinities. 



Nitric acid 100 Formic acid 3*9 



Hydrochloric acid 98 Lactic acid 33 



Trichloracetic acid 80 Acetic acid 1-23 



Dichloracetic acid 33 Propionic acid 1*04 



Monochloracetic acid ... 7*0 Butyric acid 098 



Glycollic acid 5'0 Isobutyric acid 0'92 



The order of the acids as arranged in this Table is regarded 

 by Ostwald as correct ; but he believes that farther researches 

 will necessitate considerable changes in the numbers for the 

 individual acids. 



The entrance of chlorine largely increases the affinity of the 

 acid : this is shown by the numbers 1'23, 7*0, 33, and 80 for 

 acetic, monochloracetic, dichloracetic, and trichloracetic acids 

 respectively. Similarly the entrance of oxygen into the mo- 

 lecule of the acid increases the affinity!; while the addition of 

 CH 2 decreases the affinity, as shown in the series of acids from 

 formic to butyric, and also in glycollic and lactic acids. 



The importance of the results obtained by Guldberg and 

 Waage, and by Ostwald, must be apparent to every chemist. 



In both series of researches we are taught of a coefficient of 

 affinity which is a fixed quantity for each chemical molecule ; 

 but at the same time we are led to recognize the paramount 

 importance of the physical conditions under which this affinity 

 is exercised. 



We are further presented with a tolerably satisfactory expla- 

 nation of the leading facts of chemical action, without the 

 necessity of appealing to any special and mystical " force of 

 attraction " to account for these facts. 



The modern advances in the theory of chemical action lead 

 us back more to the writings of Berthollet than to those of 

 Bergmann. Bergmann's idea that the affinity of different 

 substances may be represented by the amounts of each which 

 combine together, was evidently untenable in the fuller light 



* This result is arrived at by Ostwald's own researches and by those 

 of Thomsen, Pogg. Ann. cxxxviii. 65. 



t This is further shown by the numbers obtained for the relative affi- 

 nities of succinic, malic, and tartaric acids, which are 1-45, 2*82, and 5*2 

 respectively. 



