and the Cause of Epidemic Disorders. 123 



sooner did searching investigation into the products of the 

 saponification of butter make us acquainted with butyi*ic, ca- 

 proic, and capric acids, than the question concerning the aro- 

 mas which butter imparts to the air is actually solved. Start- 

 ing, then, from these facts, let us suppose that the air charged 

 with the odour of butter, which only affects our sense of smell, 

 was deleterious to an animal, and it wiU then be manifest, 

 that chemistry, which was incapable of discovering this miasm 

 in the air, would have succeeded in recognising it, by studying 

 the substance which produced it ; and this is an example, 

 quite in point, demonstrating that careful research may shed 

 an unexpected light upon a subject which seems absolutely 

 foreign to that of the researches more especially under review. 

 The waters which are used for drinking suggest considera- 

 tions perfectly analogous to those we have been contemplat- 

 ing respecting the atmosphere. For, in many instances, it 

 cannot be doubted that they do not merit the careful atten- 

 tion of chemists, not only on account of the very minute 

 quantities of any active ingredient which they contain, but 

 also on account of the atmospheric oxygen of which they 

 may be more or less deprived, or that they have so far been 

 deprived of the contact of air that they could not absorb 

 enough for saturation, or because they may have been mixed 

 with some combustible organic matters, which would ap- 

 propriate the oxygen they had imbibed from the sm-roimd- 

 ing atmosphere. At the same time, the great use now 

 made in many of the arts of poisonous compounds, such as 

 the salts of arsenic, copper, &c. ought to arouse attention ; 

 for it is possible that the waters which have been em- 

 ployed in washing stuffs impregnated with arsenical com- 

 positions may, in some localities, have an injurious influence 

 upon animals. It is als« possible that the same effect may 

 be produced by those substances containing arsenic, which 

 have been buried in the earth, and which, disseminated by 

 subterranean waters, may appear at the surface of the soil, 

 far from the places in which they were originally deposited. 



Consequences which may he deduced from the foregoing 

 considerations. 

 Inquiry concerning principles exerting an active agency upon 



