200 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 9 



to deal with several of the more serious objections very briefly noted 

 in my book. The replies they do give concede nothing to balance of 

 judgment in weighing argument. For instance, one can sympathize 

 with the spirit of reform in their answer under (4) ; but the force in 

 an answer of this type depends upon several factors which are not 

 apparent when the answer is isolated. Realizing that data in several 

 distinct branches of science have been recorded in thousands of cases 

 since 1909 in terms of pH and that there would be great practical 

 difficulty in establishing the acceptance of Wherry's xH scale among 

 all these sciences, one can consider the prospect of confusion to be an 

 unimpeachable argument against the suggested change so long as no 

 distinct fundamental advantage is shown. Then and then only will 

 there be found any force in answer (4). 



That no very distinct advantage is set forth by Wherry and Adams 

 should be apparent from the shifting nature of their argument. Set- 

 ting out originally to simplify the scale for "the worker in the non- 

 mathematical sciences" Wherry uses the same mathematical steps in 

 the experimental derivation of his xH that are used in the derivation 

 of the pH scale. He then introduces another scale, that of "specific 

 acidities," and at once covers up those logarithmic relationships which 

 it is of inestimable value to impress upon the student. In using this 

 specific acidity scale he naively acknowledges the false step for he 

 expresses series of soil acidities with the following series of numbers- 

 for specific acidities: 



300 100 30 10 3 1 



The "worker in the non-mathematical sciences," after reading anew 

 in Wherry and Adams' exposition of the xH scale that the specific 

 acidity scale reveals their solution 1 to contain 2000 times as much 

 acid (sic) as solution 2, will be puzzled to know why Wherry uses such 

 a peculiar series of numbers for soil acidities. 



The secret is that Wherry knows the intrinsic physical value of a 

 logarithmic scale (pH or xH) and has spaced his specific acidities to 

 correspond with 0.5 point on a logarithmic scale. In this way specific 

 acidities are made to come to the defense of xH! Wherry, in his 

 papers, has not enough confidence in the xH scale to use it. 



But a discussion of this and similar matters would be hardly worth 

 while unless the real source of our difference in point of view could be 

 reached. I believe I find it in the answer Wherry and Adams give 



2 Proc. Acad. Nat. Sci., Philadelphia, April, 1920. 



