330 TRANSACTIONS OF THE 



Chloride of magnesium, A trace 



Common salts, 3 grains 



Sulphate of lime, 2 do 



Vegetable and animal matter, 2 do 



Magnesia and carbonate of lime, 5 do 



12 grains 



I was astonished to find by this experiment how small a quantity of 

 vegetable and animal substances in the earth had been carried away by the 

 water, where they exist in solution, and cannot be separated by filtration 

 on account of the insignificant quantity mechanically suspended. This 

 water was, as may be observed by the foregoing analysis, entirely free from 

 metalic impregnations or deleterious gases ; consequently it did not become 

 oflFensive, or give rise to noxious effluvia on being kept a considerable 

 length of time, and consequently would not have contributed to disease, 

 even had it been collected in reservoirs for agricultural irrigation. There 

 was nothing in it to render it unfit as a beverage ; still it was insipid, from 

 the small percentage of lime and salt contained in it, as well as deficiency 

 of fixed carbonic acid gas. 



This is by no means the ease with the generality of drainage water ob- 

 tained from springs, rivers, creeks, &c. ; they are often impregnated to a 

 less or greater degree with foreign matters, which they hold in suspension, 

 and they usually consist of four varieties : 



1st. The mineral ; 



2d. The animal ; 



3d. The vegetable ; 



4th The mechanical. 



Filtration separates the mechanical ; the saline matter may be distin- 

 guished as alkaline ; the gypsum and salt as neutral. 



The alkaline consists of bicarbonates, such as magnesia and lime. These 

 earthy salts cause water containing them to be termed hard, and when used 

 for manufacturing purposes through the medium of steam boilers, encrusts 

 them, frequently causing explosions, and if used for washing, consumes an 

 enormous quantity of soap. Eain water, as it drops from the heavens, is 

 probably the most pure of all varieties of water, containing chiefly ammo- 

 nia. The animal, earthy and vegetable matters found in it, after having 

 passed through the drains, are extracted from the soil in its passage through 

 it, and the amount of them depends upon the constituents of the soil through 

 which it passes, and the time the water is maintained in communication 

 with the earth. 



The average annual fall of rain water in the State of New York, is about 

 twenty-six inches, half of which remains in the soil, and the other half is 

 carried ofi" by evaporation. Therefore a cubic foot of water would be an- 

 nually retained on every square foot of surface, equal to forty-three thou- 

 sand five hundred and sixty cubic feet on every square acre. It will 



