1880.] 



Water supplies of Galcnita. 



129 



hydrant water never contains more than two or at the outside three 

 parts of sodium chloride per 100,000 of water. This is proved by Dr. 

 Macnamara's analj^ses of the water at Chinsurah and Pultah, and also by 

 the numbers obtained weekly and monthly by myself. 



When however the analyses of Cossipore water are considered, it will 

 be seen that, whilst at low water in September and December, its com- 

 position is very similar to that of pure river water collected higher up : in 

 March and more particularly in June, there are very striking differences. 

 Thus on June 12th 1862 whilst at Pultah, there were only 26 parts of 

 solid impurity and 3'6 parts of sodium chloride or salt in every 100,000 

 parts of water, at Cossipore (one mile above Baug Bazar Bridge) on the 

 same day, and at lotv ivater, in the same volume there were no less than 

 97'1 parts of solid impurity, of which 55'7 parts were sodium chloride. 

 This clearly indicates that on this occasion, there was a very large admixture 

 of tidal water with the river water. Dr. Macnamara's results, as to the 

 amount of organic matter, also appear to show that in June, there was 

 much more present in the Cossipore water than in that collected at 

 Pultah, and this is really what would be expected to be the case. The 

 ratio of the organic matter shown in the two instances is greater than 2 

 to 1, and I think that this difference must indicate that the water at Cossi- 

 pore did contain an excess of organic matter over that contained at Pultah. 

 The absolute amounts of organic matter were, we now know, very much 

 smaller than the numbers given in the table, but we can probably rely, to 

 a certain extent, on the relative correctness of the numbers given. 



There appears then to be no escape from the conclusion which Dr. 

 Macnamara draws in his criticism of these results when he says — "jbhe water 

 (at Cossipore) during March, April, May and June is largely intermixed 

 with the saline matters of the sea water and the sewerage of Calcutta, and 

 during that time is unfit for human consumption." 



As before pointed out the sewage contamination would be very much 

 less at the present time than it was then, but I have tried to prove that 

 we cannot have an admixture of tidal water without at the same time 

 having organic and sewage contamination. I have no doubt that during 

 the rains when a powerful stream is running down, the water at Cossipore 

 may be nearly as pure as that at Pultah, but I think that Dr. Macnamara's 

 analyses alone prove that, during the hot weather months, the water at 

 Cossipore is by no means pure enough to be selected as a water-stipply. 



Turning now to the analyses made by Mr. Waldie, it appears to me 

 that they essentially confirm tlie results given by Dr. Macnamara. The 

 water tested by Mr. Waldie was taken usually from the river at Burranagur, 

 which is said to be two miles above Cossipore. Here on June l-lth, 1866 at 

 11-5 A. M., {at loiv tvater) 30 7 parts of solid matter, of which ll'S parts 



