Anrney—Dissolved Gases and Fermentative Changes. 281 
activity in the water. On subsequent inquiry it was found that cases of typhoid 
fever had occurred in the house supplied from the well. 
When we turn to the consideration of polluted waters in reference to the 
question of the pollution of rivers, I think it will be conceded that the experi- 
ments recorded in this, and in my previous Papers, establish beyond question the 
desirability and necessity of including, in the analysis of such waters, a deter- 
mination of the unfermented organic matters they may contain, in terms of the 
volumes of free oxygen and of carbon dioxide which will be consumed and 
formed, respectively, and also if they contain nitrogen of the ammonia which 
will be formed during their complete carbon-oxidation. 
To complete the analysis of such waters, the volume of free oxygen consumed 
during the subsequent nitrification of the ammonia may be determined, but this, I 
believe, will be found unnecessary for technical purposes. 
I trust shortly to be able to publish the results of some further experiments 
both in carbon-oxidation and in nitrification, the solutions for which have been 
preserved at blood-temperature in an incubator. 
TRANS. ROX. DUBL. SOC., NiS. . VOL. VI., PART. Xi. 2U 
