500 



the formation and distribution of poisonous particles, as well 

 as the consequences resulting from them. I consider, indeed, 

 that the greatest improvement which could be effected in the 

 sanitary condition of this country would be the one resulting 

 from such a system of thorough drainage in towns as would 

 not only carry off all refuse from the immediate vicinity of 

 the habitations of man, but which would render the surface 

 porous to a considerable depth : for I regard the disinfecting 

 powers of atmospheric air as being very superior to any 

 artificial agent we could employ, inasmuch as it will prevent 

 the formation of miasms, although it cannot destroy them. 

 In many instances we find soils containing oxydizing agents 

 in large quantities, which, in some measure, impede the 

 process of putrefaction for a time, and perform the same 

 office as atmospheric air. The peroxide of iron, in the red 

 sands of Sherwood Forest and the red clays beyond, loses a 

 portion of its oxygen by contact with decomposing matter, 

 and prevents the formation of hydrogen compounds, which 

 would be produced without them. I consider the presence 

 of peroxide of iron in a soil as a great natural disinfectant, 

 and one which, so long as it lasts, is capable of contributing 

 very much to the sanitary condition of the district. But still 

 this is not sufficient, in our present system of drainage in 

 crowded localities, entirely to prevent the production of 

 disease ; but it must tend to render districts where it abounds 

 more healthy than those where it is absent. 



I will now name another agent, naturally existing in the 

 atmosphere, to which I would not have attached much im- 

 portance had it not been generated at a time when it appears 

 to be most needed, — I allude to the peculiar compound re- 

 cently discovered by Schonbein, and which he named ozone. 

 It is a powerful oxydizing agent, produced by the electric 

 spark, — a flash of lightning, for instance, in its passage 

 through air, — and consequently will be found in the atmo- 



