

1867.] with the supply of water to Calcutta. 135 



The organic matter remaining in the mother liquors, after having 

 as well as practicable crystallised out or otherwise removed the 

 mineral saline constituents, is, in the case of the hot season river water, 

 of a pale brownish yellow colour, with a comparatively faint, somewhat 

 urinous smell ; that from the tanks and river water of the rains is of 

 a darker brown colour and a more excrementitious smell : a smell, in 

 fact, similar to that of Guana. So far as sensible properties go, the 

 latter is the more disagreeable, and according to the results of 

 experiment mentioned in the first paper, probably at least equally 

 nitrogenised. At present it would be difficult to speak more positively 

 on the subject. 



In my first paper, and more particularly in the abstract of it 

 furnished for the proceedings of the Society, I made some remarks in 

 connection with some of the tanks which my own observations will 

 not bear out. This was the result of haste and inadvertence, which 

 will now be corrected. Some of the best tanks, General's Tank more 

 particularly, are probably equal to the river water in purity at some 

 seasons, and superior to it at others. Tank water deteriorates during 

 the hot season from putrefactive fermentation ; the river water proper 

 improves from oxidation, but near Calcutta deteriorates from sewerage 

 and tidal water. Tank water improves during the rains by dilution 

 with rain water, and the animal and vegetable life in it preserves the 

 proper balance, removes decaying matters, and prevents putrefaction to 

 any great extent : at least, this is the case in good tanks. General's 

 Tank seems a well kept aquarium ; it abounds in animal life : though 

 its water has often a slightly putrid flavour, this is easily removed by 

 exposure. But even the water of that tank is not, in my opinion, 

 equal in freedom from organic impurity to the river water proper, 

 taken during the dry season at ebb tide. 



General Conclusions. 

 Before closing this communication, it may be well to make a few 

 general remarks as to the conclusions to be drawn from the data 

 obtained. It must have been observed that there is some uncertainty 

 connected with the subject of the organic matter. Persevering enquiry 

 may in time enable us to remove much of this uncertainty, but at 

 present we can only draw conclusions from the most certain grounds 

 we possess. Probably all will agree that it is advisable to get 



