224 NATURE AND LIFE. 



form the best answer that can be given to doubts on the 

 subject of medicine. We may believe, without indulging 

 illusions, that this advance will not pause. We desire no 

 better proof of it than the genuine ardor with which these 

 researches are now followed in all countries. To use Ra- 

 buteau's words, we are no longer satisfied to know that a 

 medicine cures, we wish to know also how it works a cure. 1 

 This sort of curiosity has seized upon almost all physicians ; 

 and even those who appear not to think that therapeutics 

 deserves the name of a science, willingly make efforts to 

 gain a better knowledge of the mechanism of action by 

 medicinal substances. 



Is there a relation between the chemical nature of 

 bodies and the degree of their poisoning and curative 

 power ? We can now answer this question affirmatively. 

 Certain observations, by way of experiment and conjecture, 

 had long ago been made upon this point. Thus, we knew 

 that the salts of heavy metals are more active than those 

 of light ones ; that the salts of lead and of mercury have 

 poisonous properties, while the salts of soda and of mag- 

 nesia are relatively harmless ; but this was a mere com- 

 parison, without exactitude. Rabuteau has stated with 

 precision the general relation between the physiological 

 potency of mineral compounds and their chemical char- 

 acter. The power of the soluble metallic salts is in direct 

 ratio to the atomic weight of the metal contained in the 

 salt. The atomic weights of metals being in inverse ratio 

 to their specific heats, Rabuteau's law may be otherwise 

 expressed under this form : The metals are more active 

 in proportion as their specific heat is weaker. The law 

 is the same as to metalloids of the oxygen family ; it 



1 " Elements of Therapeutics and Pharmacology," 1873 (preface). 

 This remarkable work is the first treatise published on scientific thera- 

 .peutics. It groups together with uncommon merit the latest labors 

 respecting the action and usefulness of medicinal substances. 



