64 HABIT AND INTELLIGENCE. [chap. v. 



as I am aware. If we call it x, then, the symbol of 

 common phosphorus being 



P, 

 that of red phosphorus, in the notation that I propose, 

 will be 



P + ic ^. 



NOTE. 



Inaccurate Yague and inaccurate language is still general concernuig the 

 respectins relation of chemical affinity to the various forms of energy, 

 affinity as Thus Mr. Grove says : — 



"Light, heat, electricity, magnetism, motion, and chemical 

 affinity are all convertible material affections."^ And again, 

 " Lastly, electricity produces chemical affinity." 



Now, it is quite true to say that light, heat, electricity, mag- 

 netism, and motion are all convertible, being all forms of 

 energy, and capable of mutual transformation. But chemical 

 affinities are not capable of transformation into anything else ; 

 so far as our knowledge extends, they appear to be primary 

 forces; — primary imderived properties of matter, and un- 

 changeable by any action whatever. Oxygen and hydrogen, for 

 instance, have an affinity for each other which nothing can 

 change, or transform into anything else. While they are un- 

 combined, this force of affinity makes them seek to combine ; after 

 they are combined, it resists decomposition. 



I do not susi^ect Mr. Grove of any inaccuracy as to fact, or 

 any confusion of scientific thought. I believe the expressions I 

 object to are mere inaccuracies of language, occasioned by the 

 proper technical language of the subject being not yet fixed. 

 When Mr. Grove says that electricity produces chemical affinity, 

 I presume he means that, in the electric decomi^osition of water 

 or any similar substance, the electric energy is transformed into 

 the chemical potential energy due to the mutual affinity of the 

 separated elements. 



As gravity produces motion, but motion cannot produce 

 gravity, so affinity produces heat or electricity, but heat or elec- 

 tricity cannot produce affinity. 



^ Correlation of Physical Forces, ed. 1862, p. xii. 



