M'Alpine & Hutchinson — On Vartry and Canal Waters. 85 



No. III. — From Barjcjot-afreet Bridge. 



Oxygen, 41-873 



Mtrogen, 58-127 



These results seem contrary to expectation ; for, since in coming 

 further down the canal into the city, the amount of contamination 

 increases, we would naturally expect to find a gradual diminution in 

 the relative quantity of oxygen present. But we really see that the 

 amount of oxygen, relatively to the nitrogen, is increased, the nitrogen 

 undergoing considerable diminution. How this result is to be inter- 

 preted we are not as yet prepared to say, further than that our 

 results show us that, as the contamination increases, the proportion of 

 nitrogen diminishes, while that of the carbonic acid increases by about 

 the same amount. 



It may be, that the coefficient of sohibility of the nitrogen is 

 altered, owing to the presence of such a large amount of carbonic acid. 

 But upon this point we have found no experimental data. 



These investigations were made in the Chemical Laboratories of 

 the Royal College of Science, imder the direction of Professor 

 Galloway. 



