
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.’ 
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. 

