18G7.] with the supply of water to Calcutta. 119 



Table II. For 100,000 fluid grains. 







Hardness, 



Chlorine 



calc. as 



chloride 



of sodium. 



Kiver "Waters of 





equal to grains of 







Carbonate 



of Lime. 







Total 



Permnt. 





21st August, 



Ebb, 



7.8 



*2.9 



1.58 



10th November, 



Flood, 



9.6 





1.79 



19th November, 



Ebb, 



12.7 



1.4 



.95 



9th January, 



Ebb, 



18.4 



2.1 



2.63 



11 11 



Flood, 



22.0 





4.97 



30th January, 



f Ebb, | 

 I Deep, ) 



18.5 



2.5 



1.28 



ii ii 



Surface, 



20.7 



1.7 



3.40 



20th February, 



Ebb., 



20.3 





5.63 



j j 3 j 



Flood, 



21.6 



2.6 



11.48 



2nd May, 1866, 



Ebb, 



20.0 



2.1 



15.50 



n ii ii 



Flood, 



31.4 





55.50 



This table shews the indications of the soap test already noticed 

 in the first paper. The total hardness is the effect produced on soap 

 by all the salts of lime and magnesia present, and all the carbonic acid 

 and silica ; the permanent hardness is that left after boiling, and is pro- 

 duced chiefly by the lime and magnesia not separated in the inso- 

 luble state, but still remaining in solution. Another column exhibits 

 the proportion of Chlorine calculated as if it were all in the state of 

 chloride of sodium or common salt. The chlorine is in small quan- 

 tity except when tidal influence prevails. 



So far as regards mineral constituents, the water of the Hooghly at 

 Calcutta varies greatly according to the season. Compared with the 

 waters supplying London, the solid contents during the rainy season 

 are much smaller, and the total hardness much less ; and even in 

 January and February, these are somewhat under those of the London 

 waters. As regards permanent hardness, the Hooghly water is very 

 decidedly superior to the London waters probably all the year round, 

 except possibly during the hot season at flood tide, though that latter 

 point is at present somewhat uncertain. But the temporary hardness 

 is easily removable ; and for economical use, except during flood tide 



* It nmst be remembered that these results are for 100,000 grains water. 

 For an Imp. gallon of 70,000 grains multiply by 7 and move the decimal point 

 one place to the left. 



