1 62 DOMESTIC WATER SUPPLIES FOR THE FARM 



culation, for waters to reach the deeper rocks, such waters will be 

 almost invariably more mineralized than those at higher levels in 

 the same rocks, although not necessarily more than in overlying 

 rocks of more soluble materials. Likewise, as ground waters 

 move more slowly through fine grained than through the more 

 open and porous types, they will be more mineralized in the 

 denser rocks. 



Hardness of Well Waters. As intimated above, hardness, 

 which is the property of water which causes it to form an insoluble 

 curd with soap rather than to give a frothy lather, is due largely 

 to the presence of lime and magnesia, usually in the form of bicar- 

 bonates and sulphates. The water is said to possess temporary 

 hardness when bicarbonates predominate, since upon boiling the 

 bicarbonate is broken up, the lime precipitated, and the water 

 softened. Where the mineral matter is in the form of sulphates, 

 on the other hand, the water possesses permanent hardness since 

 boiling has no softening effect. In general, water having more 

 than 250 parts per million of hardness-producing constituents is 

 inconvenient for washing purposes, although much harder waters 

 may be used for drinking with impunity. 



Water for Boilers. Many of the waters that are satisfactory 

 for drinking purposes are unfit for boiler purposes, owing to the 

 fact that the mineral constituents are deposited on heating as 

 incrustations on the inside of the boilers. There is no satisfac- 

 tory way of determining the suitability of a water for boiler use 

 other than by complete analyses. 



In New England a purer water is demanded than almost any- 

 where else in the country. In the classification of supplies used 

 by the railroads in locomotives, waters containing less than 4 

 grains of mineral matter per gallon (69 parts per million) are re- 

 garded as excellent, those of from 4 to 8 grains per gallon (69 to 

 138 parts per million) as good, those carrying from 8 to 12 grains 

 per gallon (138 to 207 parts per million) as fair and those over the 

 latter amount as unfit for boiler use. 



In other parts of the country waters that are considered unfit 



