Carbonate of Lime,. ----„- Sulphate of Lime, > Chloride of Sodium, J Oxide of Iron, 1 Silica, 1 Magnesia, Carbonaceous Matter, J Chloride of Magnesium, ) Chloride of Calcium, / Carbonate of Magnesia, - - - - - Solid matter held in solution, -'-'--' Total solid matter, Grains. 16-000 3-400 very minute portions. Grains. 16-500 2-900 Ditto. Grains. 1-42 •00 •34 •86 •70 Grains. 1-52 •44 •46 •90 •84 19-400 0-368 19-400 0-238 2-98 •34 3-70 •46 19-768 19-638 3-32 416 Schuylkill Water. In 100 parts gr. in 1 gall. Analysis of the Croton and Schuylkill waters, by J. C Booths Professor of Chemistry to the Franklin Institute of Pennsylvania, and H. M. Boye, of Phila- delphia. Croton Water. In 100 parts gr. in 1 gall. Carbonate of Lime, - Carbonate of Magnesia, Alkaline Carbonates, - Alkaline Chlorides, Oxide of Iron, Silica, Organic Matter, Parts, Alumina and Oxide of Iron, Alkaline Sulphates, 45.86 2.293 18.78 .939 16.57 .828 3.87 .193 2.21 .110 7.18 .359 5.53 .276 100.00 grs. 4.998 53.67 2.190 11.87 0.484 4.53 0.185 3.75 0.153 9.68 0.395 0.88 0.036 1.88 0.077 - 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 136 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 Croton is entirely free. There are but very few streams to be found, whose waters contain less than 4.16 grains of solid matter to the gallon. The carbonate of lime is held in solution by carbonic acid, forming bicarbonate of lime. By boiling, this acid is expelled, and the carbonate of lime is precipitated on the sides of the vessel, constituting the fur of the tea-kettle, and the crust of boilers. River water always contains a quarter or less quantity of organic matter in suspension or solution. As a general rule, the quantity is too small to produce any decidedly injurious effect, but physicians and medical writers agree in the opinion that water impregnated with it to any great extent must be deleterious. Where the quantity of decomposing matter is too small to produce any immediately obvious effects, it is difficult to pro- cure any decisive evidence of its influence on the system. When the amount is con- siderable, it causes dysenterj' and fevers, often of a highly fatal character. In a trial at Nottingham, England, in 1836, it was proved that dysentery of an aggravated form, was caused in cattle by the use of water contaminated with putrescent vege- table matter, produced by the refuse of a starch manufactory. The fish, (perch, pike, roach, dace, «fec.,) and frogs in the pond, through which the brook ran, were destroyed, and all the animals which drank of the water became seriously ill, and many of them died with the symptoms of dysentery. It was, moreover, shown, that the animals sometimes refused to drink the water, that the mortality was in propor- tion to the quantity of starch made at different times ; and that subsequently, when the putrescent matter was not allowed to pass into the brook, but was conveyed to a river at some distance, the fish and frogs began to return, and the mortality ceased among the cattle. There are many instances on record where troops have sickened and many died of putrid fever and dysentery, from drinking the water of stagnant pools and ditches or of rivers, as of the river Lee, near Cork, (Ireland,) which, in passing through the city, receives the contents of the sewers from the houses, and is otherwise unwholesome. 137 The organic matter contained in river water consists chiefly of the exuviaj of animal and vegetable substances, but another class of impurities consists of living beings, (animals and vegetables.) The aquatic animals, which have, from time to time, been exhibited in this