SANITARY ESSENTIALS. . 325 



wliich it absorbs in its descent through air and earth to 

 reach its level. It will therefore vary in purity. It may be 

 fresh or saline, hard or soft, free from or loaded with organic 

 or inorganic impurities, suitable for the use of man, or so 

 polluted as to be dangerous to health and life. It is purified 

 by percolating through sand and gravel, and by oxidation. 

 It moves through the earth in currents, varying in velocity 

 by obstructions presented by the different physical conditions 

 it encounters in its course to the sea. 



Its probable purity can be generally ascertained by exami- 

 nation of the soil, rocks, and wells in the vicinity. 



If necessary, pits may be dug to expose the character of 

 the underlying strata for inspection. If gravelly, and free 

 from alluvial deposit-sand mixed with clay, infiltrated with 

 vegetable products, and free from soluble inorganic mate- 

 rials derived from the disintegration of limestone and ferru- 

 ginous rocks, and if the locality can be protected from an 

 influx of surface-water, and pollution by filth, a well may 

 be sunk to below the level of the ground-water, that will 

 afford an abundant supply, suitable for house and farm pur- 

 poses, which will yield for centuries its pure life-giving 

 treasure to generation after generation, who will 



" Find it the source of an exquisite pleasure, 

 The purest and sweetest that Nature cau yield." 



From whatever source our water-supply is obtained, con- 

 venience requires that it should be conducted through pipes 

 and conduits to the place of use at house and barn. These 

 may be made of wood, cement, earthen-ware, lead, block tin, 

 iron, gutta-percha, and other materials. 



The well-sweep and "old oaken bucket" of our fathers 

 has been supplanted by the more convenient pump of wood, 

 copper, or iron. The aqueduct made of logs, to bring the 

 waters of the hillside spring or brook, has been exchanged 

 for pipes of lead, iron, or earthen-ware. 



We should be careful not to lose in purity of supply, by 

 our new methods, what we gain in permanence, and economy 

 of outlay. Of all materials used for conduits, lead is the 

 most dangerous to health and life. 



Pure soft water, and waters charged with carbonic acid, 

 the chlorides, nitrates, sulphates, and organic matters, act 



