266 CHURNING AND WASHING BUTTER 



as its germ-content is concerned, is in many cases turbid and 

 sandy, and needs to go through a process of purification as much 

 as does the shallow well water. 



METHODS OF PURIFYING WASH-WATER 



There are two practical and effective methods of purifying 

 wash- water, viz., (i) Filtration, and (2) Pasteurization. Which 

 of these two methods is the most practicable and the most 

 effective in the creamery depends upon the conditions and upon 

 the quality of the water. In the case of water from deep wells, 

 which contains little or no organic matter, but at the same time 

 is infested with undesirable germs, pasteurization is perhaps 

 more expedient. Filtration, if the same degree of thoroughness 

 is to be reached as in pasteurization, is a comparatively slow 

 process. Pasteurization of wash- water is a trifle more expensive 

 than filtration. Wash-water can be pasteurized at the same 

 time that the churning is being done, thus economizing in time 

 and fuel. Pasteurization is quite effective in rendering the water 

 germ-free, but it is not so effective in removing any organic 

 matter or other tangible impurities which may be present. If 

 the creamery does not already have a pasteurizer, filtration can 

 be employed very profitably, and under average conditions it 

 will perhaps give the best results. 



Filtration. Filtration is inexpensive, and is a very efficient 

 method of purifying wash-water. It seems strange that bac- 

 teria can be removed from water by passing through layers of 

 sand, gravel, coke, and charcoal, but such is the case. Filtra- 

 tion is applicable to all kinds of water; even if the water appears 

 pure, it is well to filter it. Fewer germs and fewer varieties 

 of micro-organisms are apparently found in deep well water 

 than is the case in water from surface-wells; hence the ferments 

 which are present will have a free field for developing in the 

 absence of competing forms. If a sample of water which is 

 rich in micro-organisms is violently shaken with a certain 

 amount of charcoal, coke, chalk or similar substances, and then 

 left for a time to settle, the pure layer of water at the top will be 



