Carbonate of Lime, - 45.86 2.293 53.67 2.190 Carbonate of Magnesia, 18.78 .939 11.87 0.484 Alkaline Carbonates, - 16.57 .828 4.53 0.185 Alkaline Chlorides, 3.87 .193 3.75 0.153 Oxide of Iron, 2.21 .110 Silica, 7.18 .359 9.68 0.395 Organic Matter, 5.53 .276 0.88 0.036

Parts, 100.00 grs. 4.998 Alumina and Oxide of Iron, 1.88 0.077 Alkaline Sulphates, - 13.74 0.560

Parts, 100 grs. 4.080

The Croton water was taken from the Croton dam, and when perfectly clear was found, as appears by the above analysis to contain 4.998, or about Jive

grains of solid matter to the gallon. The Schuylkill water was taken from the middle basin on Fair Mount, and contained 4.08 grains of solid matter to the gallon. The Croton differs from the Schyulkill water in containing a larger amount of the alkaline carbonates, and of the carbonate of magnesia, while it contains less carbonate of lime, and is entirely destitute of the alkaline sulphates, of which the Schuylkill contains 13.74 parts in 100 of the total

solid matters, though amounting to only one half a grain to the gallon. It appears from the above table, that the amount of impurities contained in the Thames water, exceeds those of the Croton by nearly six fold, and that the quantity of lime, held in solution in the former, surpasses that of the latter, about fifteen

times. The Thames water differs also from the Croton, in the circumstance that it contains an appreciable quantity of chloride of sodium, or common salt of which the