ApENEY— Organic Matters in River Waters. 343, 
method of examination, compared with those hitherto in use for the 
examination of river waters, places in the hands of chemists for 
gaining a knowledge of the true character of the fermentable 
matters to be found inriver water. I would, however, again draw 
attention to the important fact which I dwelt upon in my first 
communication, viz. that it is possible to determine by means of 
this new method not only the total volume of oxygen required for 
the complete oxidation of the fermentable matters, including 
ammonia, in water, but also to distinguish the portion consumed 
during the first stage of fermentation from that consumed dur- 
ing the record stage—a distinction, for reasons I have already 
given, of the utmost importance in connection with the technical . 
consideration of the pollution of river water. 
