OF WATER FOR ORGANIC MATTER. 49 



subject before me frequently since that period, namely, 

 1847, ^^* have never given it all the time required for 

 its elucidation. Lately Professor Wanklyn and Messrs. 

 Miles, Smith, & Chapman have examined the hill- waters, 

 and have rather alarmed the public by informing them 

 that they contain more albumenoid matter than waters 

 coming from rich plains. The process they adopted has 

 no doubt shown two conditions of the nitrogen ; and it is 

 possible that one was to be found as albumen; but it 

 seems perfectly clear that it was not putrescible albumen. 

 I had long ago found the nitrogen ; it still remains to find 

 out all the conditions of its existence. If waters contain- 

 ing nitrogen from the hills are allowed to stand, they 

 neither show their nitrogen by the production of living 

 forms in proportion to the amount of that element, nor by 

 putrefaction ; any fear, therefore, of such results may be 

 entirely put out of our minds. The living forms, which 

 are the most dangerous, are fewer than from pretty deeply 

 filtered water of the plains ; and putrefaction cannot exist 

 when the matter to putrefy is so minute : when the solutions 

 are extremely weak, oxidation overpowers it. Such, at 

 least, is my experience. 



And now let us consider what does take place during 

 putrefaction. In all cases known to me, the first thing 

 that occurs is the diminution of oxygen in the air 

 absorbed by the water, and, to a more or less extent, 

 the production of sulphuretted hydrogen, which, however, 

 may exist in the water to a very small extent at a time, 

 being rapidly converted into combined sulphuric acid 

 when oxygen can be found for the purpose. 



In Loch- Katrine water the oxygen found in the absorbed 

 air by Dr. Penny was equal to 31 '69 per cent.; that of 

 the Manchester water is equal to 27 per cent. In the Liver- 

 pool water, at the bottom of the reservoir, the amount 

 fell to 12 per cent., being equal on the surface to the Mau- 



SER. III. VOL. IV. E 



