1866.] Proceedings of the Asiatic Society. 221 



Macnamara had caused the specimens of the river water to be drawn, 

 upon which his experiments had been made. 



Dr. Smith said he had Dr. Macnamara's Report before him, in which 

 the preliminaries of his operations were most plainly laid down. 



" The water was taken monthly, from the centre of the stream, at six 

 feet below the surface, and from three stations, namely, from opposite 

 Cossipore, Pultah Ghaut and Chinsurah." 



Dr. Smith thought the Society ought to be glad that so important 

 a subject had been brought forward, one not of mere abstract scientific 

 interest, but related to questions of very great practical importance. 



It was note-worthy that the largest quantity of organic impurity at 

 any time detected by Mr. Waldie was 1.4 of a grain per gallon, 

 whereas the following was the result which had been arrived at by 

 Dr. Macnamara with Cossipore water : — 



" As might be expected, the water during March, April, May and 

 June, is largely intermixed with the saline matters of the sea- water 

 and the sewerage of Calcutta, and daring that time is unfit for human 

 consumption. * * ■ * * * The saline contamination is not of 

 such importance with regard to the use of Cossipore water for drinking 

 purposes, as is the pollution which the water derives from the sewage 

 matters, which the tide sweeps along with it. * * I found during 

 last April, as much as 10 and 12 grains of organic impurity in the 

 water." * * The organic impurity of Cossipore is highly nitro- 

 genised, and while burning, evolves a strong and disgusting ammonia- 

 cal smell." 



Here is a grand discrepancy, the true cause of which it would be 

 well that the Asiatic Society should try to discover. Dr. S. was inclined 

 to believe that the fact of Mr. Waldie's experiments having been post- 

 poned after the drawing of the water to weeks and even to months, was 

 sufficient to account for the difference in the results now contrasted. 

 Dr. Macnamara's observations had extended oyer fourteen months, and 

 he had used water freshly drawn. 



The conditions under which Mr. Waldie had gone to work were quite 

 dissimilar to these. 



Mr. Waldie had said he thought it simply impossible that the water 

 of the Hooghly could be impregnated with so much as from 5 to 8 

 grains of organic impurity in the gallon. Dr. Smith was disinclined 



