178 



It is interesting to notice in these last two tables, and the 

 remark on Sulphurous acid, the sharp line of demarkation 

 between the amount of acid contained in water in which 

 life can originate and that which totally prevents origination. 



In tlie case of Sulphuric acid we find that the small 

 amount of 0-010 grms. per litre in addition to the ordinary 

 acidity completely prevents it, whilst, in the case ot 

 Hydrochloric acid, 0005 grms. per litre is sufficient. In the 

 case of Sulphurous acid the author could not get life to 

 originate in water containing any of that acid, 



