JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. 9 JULY 19, 1919 No. 13 



THYSICS.— "Physical" vs. "chemical" forces. P. V. WELLS, 

 Bureau of Standards. (Communicated by S. W. Stratton.) 



In his remarkable memoir on the constitution of solids and 

 liquids, Langmuir^ considers in some detail those forces which 

 are concerned in the structure of matter, stating their charac- 

 teristics with great clearness. But unfortunately he adopts 

 definitions of "physical" and "chemical" forces connoting a 

 narrowness to the term "physical" which is quite unhappy. I 

 realize, however, that his purpose in this is to emphasize the 

 relation of many terms and phenomena usually regarded as dis- 

 tinct. 



Science has arrived at a stage in its evolution where the classi- 

 fication between physics and chemistry appears artificial. Of 

 course all classification is necessarily arbitrary and appears so 

 especially at the boundaries between classes. There must, 

 therefore, be confusion and difference of opinion among those 

 who approach the study of what may perhaps be called twin 

 fields, such as physical chemistry or chemical physics, from differ- 

 ent points of view. The appropriate attitude in such matters 

 seems to be to avoid the artificial issue by classification and nomen- 

 clature derived from a viewpoint common to both. 



In view of the historical significance of the words "physical" 

 and "chemical," their use in classifying forces appears rather un- 

 natural. A less artificial nomenclature is that derived from the 

 fundamental theory of the constitution of matter common 



1 I. Langmuir. Jotirn. Amer. Chem. Soc. 39: 184S. 1917. 



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