134 Mr. Waldie's Investigations connected [No. 2 



nature ; non-nitrogenised matter. It appears to me, however, that 

 there is a tendency generally to make too much of this distinction 

 between matter of vegetable and of animal origin, it being often 

 spoken of as if the organic matter were of little importance, if it could 

 be shown to be vegetable matter. Now it may be admitted that 

 most probably water tinged by peaty matter consisting of the ordinary 

 humous class of acids and salts, may be not at all even injurious to 

 health, and .that water flowing over or percolating through the soil 

 of mountainous districts or others bare of vegetation, where there is 

 little herbage and much earth or rock, maybe very pleasant and 

 wholesome. But citing such cases is only evading the question. 

 It does not follow that water draining off cultivated fields or dense 

 jungle, or flowing between banks covered with luxuriant and rank 

 vegetation, will be equally harmless. Putrefying animal matter is very 

 offensive, but putrefying green vegetable matter, though not so 

 disgusting in idea, is scarcely less offensive. Nor, be it remembered, 

 are the poisonous properties very much dependent or connected with 

 a disgusting taste or smell, and the most powerful poisons come from 

 the vegetable kingdom. 



In my first communication, the oxidising action of the atmospheric 

 air dissolved in river water was brought forward as a powerful agency 

 for purifying the water. And though Dr. Frankland's results were 

 quoted as strikingly illustrating it in respect to the Thames ^Waters, 

 yet such observations are by no means new. And it must again be 

 observed that the high temperature of the climate will materially 

 assist this action. No doubt it assists putrefaction, fermentation also, 

 and in some cases this may take place in a river, when its course from 

 any cause is rendered very slow. But in the case of the Hooghly 

 the tides cannot fail to act beneficially ; twice every day damming 

 back the water and again retreating, enabling the river to flow with 

 increased velocity, increasing the motion amongst its waters and 

 constantly changing the surfaces exposed to the air. This is just 

 one of those agencies that escape general observation : it does not j 

 exhibit itself to the senses, yet it must be remembered that it is | 

 by the oxygen dissolved by water, small though that be in amount, I 

 that animal life is preserved in the waters no less than in the ordinary; 

 atmosphere. 





