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Potable Water.

Local boards of health, and those having an analysis of water made for potable purposes, should make a note of these figures, and of what they represent, as they are sufficiently accurate for practical use.

In explanation of the above table, it may be said that good water may contain an excess of organic carbon, but if the proportion of nitrogen as nitrites or nitrates and chlorine are low, the indications are the organic matter is of vegetable origin, and therefore harmless. If the chlorine and nitrogen are high, as in the second table, the organic matter unquestionably comes from animal matter. Nitrogen as nitrites should be absent in good water, from nine tenths to one and one tenth parts per one hundred thousand of nitrogen, as nitrates constitute an excess, and no water containing this amount should be used for potable purposes.

The amount of chlorine in bad water varies from three parts to several per one hundred thousand. Chlorine is evidence of sewage pollution. Water may contain much less than this and yet be polluted from sewage. As a rule, it may be said that a high rate of chlorine is always accompanied with a high rate of nitrogen as nitrates.

The presence of an excess of ammonia, especially albuminoid, is suspicious, and should be governed by the same rule as applies to organic matter, whether it be from animal or vegetable source. Usually it comes from sewage, the organic matter of sewage being of an albuminoid nature, and the quantity present indicates the lack of oxidation of the original matter by percolation through the soil.

While it is true, as a general proposition, that water largely polluted with organic matter may become purified and rendered harmless by percolation through soil, there is constant danger that shallow wells so-called, will be polluted by organic matter which finds access to it, during heavy rain falls, unoxidized. This is especially liable in cities and towns where privy vaults and wells are sunk side by side, and stables and hog-pens contiguously abound. Hence it is, that fevers of malarial type prevail more extensively in wet than in dry seasons.

Potable Water.

It should be borne in mind that no amount of percolation, or oxidation will purify water polluted by human excrement, or destroy the specific germ, or poison of Typhoid Fever. It may be carried long distances and at great depth of soil.

For sanitary purposes, the State Board of Health has fixed the following

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Oxygen required to oxidize organic matter per three hours at 30 deg. Fah......

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Microscopic examination of floating matter to be made.
The topography of entire area of surface to be considered.

The United States gallon to be deemed fifty-three thousand three hundred and eighteen grains.

The limited means at the disposal of the State Board prevents, entirely, any general work, in ascertaining the character of the public and private water supply of the State. Than this, is scarcely another subject more important to the public health, or more clearly within the purview of the legitimate work of the board. Something more than a simple chemical analysis is necessary to a correct and satisfactory conclusion as to the condition of water, and no competent and intelligent chemist will render judgment upon a sample of water for potable use, from his analysis alone. For example, chlorine is an important factor in estimating the character of water for sanitary purposes. It is present in all natural water. It may be derived from the geological formation through which it passes. That it is present in large quantity has really no significance whatever. The important point is from whence the chlorine comes-whether vegetable are animal.

Potable Water.

A history of all the sources and surroundings of water is therefore of the utmost importance, in establishing the character of any water, and frequently is of more value than a chemical analysis. A well in a sandy, porous soil, or even stratified rock, in near proximity to privies and cess-pools, may contain water chemically not bad, yet be dangerously infectious, from microbes or disease germs so minute as to escape arrest by soil filteration, and to be detected only by the microscope.

In explanation of the figures expressing the constituent parts of water, as given by chemical analysis, the following will be of aid to the public:

Total Solids.-The total solids is the residue left after throwing off by evaporation a measured quantity of water, and consists of the inorganic and organic matter in the water. Though desirable to have it low-the quantity-it has no positive significance as to the quality of the water, unless it be excessively high. A high proportion of solids in river water would be suspicious, yet have no significance in that from an artesian well.

Loss on Ignition.-This is the residue left of the solids, after a red heat to burn the organic matter, and dispel the volatile parts of the inorganic matter. Its value consists chiefly in the odor given in the process of heating, whether it be from animal products, or from vegetable material.

Hardness.-The hardness of water has very little hygienic significance. The popular notion that hard water conduces to the formation of urinary calculi, is disproved by surgical experience.. In Philadelphia, Dr. D. Hayes Agnew, the eminent surgeon, reports the majority of cases of this disorder, in a district in Philadelphia supplied with soft water.

Chlorine. This is a large constituent of common salt. Its presence in water is not conclusive of contamination. Water from deep wells and springs may contain a high proportion of chlorine, and yet be healthful. It is to be considered in connection with the ammonia, nitrates and nitrites. Its presence is suspicious, but a water is not to be condemned thereby, unless confirmed by the history of the source and the surroundings.

School-house Water Supply.

Ammonia. This is derived from organic matter in the process of decomposition: An excess of two thousandths parts in one. hundred thousand should cause an investigation of the surroundings of the water supply. Albuminoid ammonia suggests pollution with animal organic matter, or the direct mixing of sewage with the water, either directly at or near the source of water supply, or by soil percolation.

Nitrogen as Nitrates.-This is one of the stages in the reversion of organic into inorganic matter, ammonia being the first.

Nitrogen as Nitrites.-This is the third stage in the reversion above mentioned, and its presence suggests that the soil has failed to oxidize or filter out the infective or polluting parts. It should not be present in potable water.

In all cases, judgment for or against a water can only be given after a careful consideration of the history thereof, together with the aid of the microscope.

SCHOOL-HOUSE WATER SUPPLY.

One of the most potent causes of Diphtheria and Scarlet Fever in this State during the past two years was unquestionably the low water in wells and streams, thereby rendering them more liable to contamination.

This contamination of the water supply leads to a condition of general ill-health, and thus renders those using it more susceptible to the influence of those factors producing specific diseases. The superadded presence of an infectious disease is all that is needed to inaugurate an epidemic.

In dense communities this is a matter for serious consideration, and especially with reference to public schools. There is probably not a well upon a school-house lot within the State that is not suspicious, if not actually contaminated, surrounded as they usually are, by privies, stables and filthy back alleys of adjoining lots.

Milk.

A portion of the wells are driven wells, which afford no security whatever from pollution-in fact are worse than dug wells properly constructed. In view of the importance of this matter, as a sanitary measure, it is suggested that the State Board take some action thereon, and that recommendations, if not positive regulations, be made for school-houses to be supplied with water from water-works in all cities and towns where water-works are in operation, especially when analysis shows the water to be of good quality, and safely potable.

Village and country schools should have the well at least one hundred feet from any privy or stable, and the topography of the contiguous surface should be such as to secure rapid and free drain age in every direction from the well for the farthest possible distance. It should be free from the shade of trees and accessible to uninterrupted air currents.

MILK.

It is an inherent, a sovereign-it may be said a natural right of individuals and communities to know the exact character of what they eat and drink, and to require that they shall be healthful. This right is founded in the law of self-preservation. In proportion therefore, as an individual or a community guard themselves by rigorous surveillance over the producers or dealers in these, so will they be improved, and so will be the measure of their health.

Cows' milk is one of the most important elements of the daily food of the people, and far more important, it is the very life of the large majority of children, and with whom the quality is a question of life and death.

Pure and wholesome milk cannot be obtained except from a perfectly healthy animal. To preserve and maintain the health of a cow she must have good food, pure water, fresh air, light, daily

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