128 MODERN DAIBY PRACTICE. 



creamery clean. But, especially during the spring floods, 

 many of our factories have to be satisfied with an impure 

 water, rich in micro-organisms which may directly con- 

 tribute to the infection of the factory. 



As we have seen before, water is generally an excellent 

 nutritive medium for a large number of bacteria, which 

 thrive the better in it the more it is polluted with organic 

 substances and the less it is exposed to the air. We often 

 see brick-laid wells covered so that ventilation is rendered 

 entirely impossible. I have heard complaints of the quality 

 of the water at every factory where I found this was the 

 case. In the Danish bill for Co-operative and Proprietary 

 Creameries previously mentioned it is stipulated that the 

 wells of the creameries should be located in such a way as 

 to prevent impure water from flowing into them. New 

 creameries are to be located only where plenty of good 

 water may be obtained. 



The solid particles and impurities found in the wells 

 seem to affect the bacteria content of the water. It has 

 been proved by special investigations that bacteria in wells 

 multiply best in the immediate neighborhood of solid 

 matters, even if these are as unfit for nutrients as stones. 

 A properly-kept well ought therefore to be free from all 

 unnecessary solid substances. It is further of importance 

 that the well be not long left unused. The best way to 

 keep the water pure in a well is of course to empty it as 

 often as possible. Heraeus says on this point: The best 

 well may, if used only a little or not at all, yield water with 

 thousands of bacteria capable of reproduction in every 

 cubic centimeter, and the poorest well may be so improved 

 by continual pumping that its water will contain but few 

 bacteria. 



