17o 



The animals upon which the experiments were tried were 

 the rotifers (rotifer vulgaris). 



A certain amount of air was washed with distilled water 

 and life allowed to originate in the solution, so that it could 

 be seen at once what influence the amount of acid usually 

 found in air had upon the life. 



As a rule it required five days to bring the rotifers to 

 perfection. The method of experiment was very simple. 

 After animal life had been procured in the solution a 

 known amount of the various acids used was then added, and 

 allowed to stand one day, this was repeated till enough had 

 been added to destroy life. 



The results of these experiments are embodied in the 

 following tables : — 



TABLE I. 



SULPHURIC ACm ADDED. 



