. Preventive medicine and hygiene. ities having an abimdantwater supply. This danger was well shown in the studies upon typhoidfever in the District of Columbia, in which many of the shallow wellssituated within the city limits were shown by chemical and bacterio-logical analyses to be polluted. Wells may be disinfected with lime, which has been found to befairly effective. A mixture of carbolic acid and sulphuric acid in suffi- \ SOURCES OF WATER 815 cient quantity will sterilize a well, but these substances have evidentobjections. The method of injecting steam under a pressure of twoatmosphe
. Preventive medicine and hygiene. ities having an abimdantwater supply. This danger was well shown in the studies upon typhoidfever in the District of Columbia, in which many of the shallow wellssituated within the city limits were shown by chemical and bacterio-logical analyses to be polluted. Wells may be disinfected with lime, which has been found to befairly effective. A mixture of carbolic acid and sulphuric acid in suffi- \ SOURCES OF WATER 815 cient quantity will sterilize a well, but these substances have evidentobjections. The method of injecting steam under a pressure of twoatmospheres has been used. The steam is forced into the water untilthe temperature is brought to near the boiling point. Bleaching powder,however, is the cheapest and most practical method of disinfecting wellsthat need such purification. Springs.—A spring is a stream of water emerging from the ground,its flow being due to natural causes. Spring water does not differ inany essential particular from the ground water obtained from shallow. Fig. 102. -In a Limestone Formation It Is Difficult to Tell Anything abotjt iheSource of Water Obtained from a Well. wells. Springs may be regarded as natural wells, outcropping wherethe geological formation is favorable. Spring water, as a rule, ia of ahigh degree of purity, and as the water flows spontaneously it can easilybe utilized; and, as no form of machinery is necessary to pump it, it isless subject to contamination than well water. Spring waters differgreatly in character, depending upon the temperature of the waterand the inorganic constituents which it contains. Springs may beperennial, the flow being constant or intermittent. Fuller classifies springs, according to their origin, as gravity andartesian; and according to the kind of passages traversed by the water,as (see page 811) tubular and fissure springs. Some of the largest flowing springs are found in Florida, notableamong these being the Silver Spring with an estimate flow of 368,9
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
