SANITARY MILK PRODUCTION 169 



TABLE 50. APPROXIMATE QUANTITY OF WATER REQUIRED PER DAY ON THE FARM 



Gallons 



Each member of family for all purposes 25-40 



Each cow 12.0 



Each horse 10.0 



Each hog 2.5 



Each sheep 2.0 



This makes no allowance for water for steam making or for washing dairy utensils 



Most ground waters are hard because the water, being long in con- 

 tact with the rocks through which it makes its way and, in the case of the 

 deeper waters, being under pressure, dissolves mineral substances from 

 the earth. Some ground waters are only slightly mineralized while others 

 are so heavily charged with mineral substances as to be entirely unfit 

 for use. Hard waters increase soap consumption and also the cost of 

 operating steam boilers for they deposit hard or soft scales that in- 

 crease the fuel consumption and injure the boilers. Some waters cause 

 foaming, while others corrode boilers and sometimes cause them to 

 explode. In many steam plants, boiler compounds and corrective 

 measures of various sorts are applied to make the water usable. In 

 many industries the mineral content of water has a deleterious effect 

 on the product manufactured. At the South Dakota Station the effect 

 of alkali water in making butter and cheese and also on the cow and 

 her milk was studied, but no unfavorable results were observed to attend 

 its use. 



Contamination of Milk by Ice. Ice is used liberally in many dairies; 

 in fact in summer it is all but necessary. Care should be taken to have 

 it pure. The late Thomas M. Drown showed that ice in freezing has 

 a decided tendency to exclude impurities, but he found this action to be 

 most marked in the layers that are formed by the slow growth of the 

 ice downward, because the surface in its rapid congealing entangles 

 suspended matter, particularly if the water is stirred up by the wind. 

 Moreover, if the ice is frozen after surface flooding, which is frequently 

 brought about intentionally by the harvesters, it will contain all. of the 

 impurities of the water so added. In making artificial ice in the ordinary 

 way, the entire body of water is frozen and all the impurities are concen- 

 trated in the last part of the cake to freeze. Hence an impure water is 

 especially undesirable for ice manufacture. Likewise, when shallow 

 ponds freeze solid, the impurities are concentrated in the bottom ice. 

 Sedgwick and Winslow proved that typhoid bacilli perish rapidly in ice, 

 even 98 per cent, of them dying in 2 weeks. This indicates that there 

 is little reason for fearing that this disease may be introduced into the 

 dairy by ice and the fact that there is no perfectly clear case of typhoid 

 fever having infected a milk supply through the medium of ice is con- 

 firmative of this view. Artificial ice, being often used without storage, 



