MEDICAMENTS AND LIFE. papi, 
is inverse for those which are related to chlorine, and for 
those of the arsenical class. This untiring investigator, in 
order.to establish these laws, undertook experiments six 
years ago, which have been steadily followed up till. very 
lately ; and the Academy of Sciences has recognized their 
discovery by a brilliant reward. Their practical interest 
may easily be estimated. When a physician, in future, 
has need to choose between different salts, all that will be 
required will be to consult a table of atomic weights in 
order to learn at once their respective activities, and con- 
sequently to fix upon the proper dose of them. When a 
physiologist wishes to test the action of a metallic com- 
pound, he will be able to foretell its relative intensity, and 
thus to guide his use of it in experiment. When the effect 
of salts of thallium was tried upon animals some years ago, 
this being one of the metals just revealed by spectrum 
analysis, it was noted with much surprise that these salts, 
so extremely similar in other respects to those of soda and 
of potassa, were yet powerfully poisonous. This is because 
the atomic weight of thallium is very high; its poison- 
ing potency is thus in exact agreement with Rabuteau’s 
law. 
The improvement of the healing art is thus allied in 
the closest way with the advance of our knowledge as to 
the true action of toxic and medicinal substances. To 
enlarge this knowledge, we must follow Bernard’s ex- 
ample and. methods: in: the ‘examination of effects pro- 
duced upon animal: tissues. It is of moment; too, as Du- 
mas recommends, to test’ the action of all- those new sub- 
stances which organic chemistry has been for some time 
producing, several of which undoubtedly carry in them 
medicinal qualities. The study of these effects is very re- 
fined, and those savants who undertake it will need to 
handle with equal skill the instruments of physics, of physi- 
ology, and of chemistry. The point is not simply to analyze 
