216 PESTILENTIAL DISEASES. 



tliese are producing some dire effect, and when we 

 know that these secondary causes may be modified, it is 

 sufficient evidence to prove that man is permitted to 

 control thus far the afflictions which are sent to try his 

 powers. 



We find a disease winging its way from lane to alley 

 and closed court, sweeping with destructive violence its 

 way through damp cellars and crowded attics ; it is rife 

 with mischief along the banks of reeking ditches, and 

 on the borders of filthy streams. Certain it is, therefore, 

 that some ultimate connexion exists between the con- 

 ditions of dirt and this speedy death. Can science tell 

 of g these ? has it yet searched out the connecting link ? 

 Let the question be answered by a few facts. 



When the cholera first made its appearance, and 

 subsequently, it has been observed that the electrical 

 intensity of the atmosphere was unusually low. 



The disease has departed, and it is then found that 

 the electricity of the air has been restored to its ordinary 

 condition. 



This appears to show some connexion; but how do 

 these conditions link this physical force with the ditch- 

 seeking disease ? 



From all stagnant places, from all the sinks of over- 

 crowded humanity, from fermenting vegetable and from 

 putrefying animal matter, there are constantly arising 

 poisonous exhalations to do their work of destruction. 



Where death and decay is a law, this must of necessity 

 constantly occur ; but the poisonous reek may be dif- 

 fused, or it may be concentrated, and Nature has pro- 

 vided for this, and ordered the means for rendering the 

 poison harmless. 



By the agency of electricity,- probably, too, by the 

 influence of light, the oxygen in the air undergoes a 

 peculiar change, by which it is rendered far more ener- 

 getic than it is in its ordinary state. This is the con- 

 dition to which the name of oz one has been applied. 



