200 Proceedings of the Asiatic Society. [Sept. 



were in pretty fair accord, and agreed in indicating most organic 

 impurity in the water of the rainy season, decreasing continuously 

 after the rains, as the season advanced. This decrease was not so well 

 observed in the weight, which was indeed greater during May and 

 June, but only to a small extent ; and this, it was considered probable, 

 might be rather apparent than real, and owing to practical difficul- 

 ties in the process and the large quantity of saline matter from the 

 sea mixed with the water. At all events, according to the author's 

 results, the amount of organic matter in the river water on the 14th 

 June last, at flood tide, at the extreme height of the hot. season, 

 was only from 1 to 1J grains per gallon. These results were very 

 different from those generally received, which supposed a minimum of 

 organic impurity during the rains, gradually increasing, and during 

 the hot season rising to eight, ten, or even more grains per gallon. 

 But they were quite in accordance with the latest results of the exa- 

 mination of the London waters by Professor Frankla-nd, who found 

 that " the waters in question are much purer in dry than in wet 

 weather, even if the drought occurs during a very hot summer." And 

 on consideration it is found to be in accordance with what may be 

 expected. During the whole dry season, both cold and hot, the pro- 

 ducts of vegetable and animal decomposition have remained in the 

 soil and accumulated, but when the rains come they are washed off 

 into the river, both in solution and suspension. When the rains cease, 

 the impure mud subsides, and the oxygen, freely absorbed by running 

 streams, oxidizes the organic matter in solution and purifies the water. 



The nature of the organic matter was then enquired into, — namely, 

 its vegetable or animal origin. The latter was considered the most, 

 dangerous kind, and the means of judging of its presence considered. 

 The presence of Ammonia was considered a good indication of the 

 existence of animal matter, and some examinations for determining its 

 proportion had been made ; the proportion in the Hooghly water 

 was small. Other means of estimating the amount of animal matter 

 indicated the same thing. 



The question as to the extent of contamination of the river water 

 during the hot season under tidal influence, by the sewage of the town 

 was considered, and the author had come to the conclusion that at the 

 very height of the hot season the water was no worse, as regards 



