88 



The milk used was better than the average, varying 

 from 2.5 to 18.5 milligrams dirt per liter, while the milk de- 

 livered in Hamburg market for 1898 varied from to 183.5, 

 with an average of 13.5 milligram per liter. The result of 

 eight tests showed on an average 9.5 milligram dirt in the 

 new milk and 1 in the centrifugated milk. 



Experience has shown that there is no need of employ- 

 ing specially constructed separators, as those used for skim- 

 ming will do the work satisfactorily; thus Mr. H. B. Gurler 

 uses a No. 3 Alpha De Laval in his sanitary dairy. 



There has been some fear of difficulty in getting the 

 milk and cream mixed again, but if the two streams are 

 run together and passed at once over a cooler, there will be 

 no trouble. A great advantage of this system is that it puts 

 it in the milk man's power to deliver milk of a guaranteed 

 percentage of fat by either removing part of the skim milk, 

 or, in case of very rich milk, part of the cream. 



It is true, this system requires power steam or hand 

 but it is certainly the very best one for cleaning milk. 



PRESERVING THE MILK FOR DELIVERY. 



Having purified the milk by either of these mechanical 

 means, the next step is to secure its preservation. As said 

 before chemical preservatives should never be used it is ille- 

 gal as well as immoral, and the simplest and best system is 

 cooling it at once as much as possible. 



FARM COOLERS AND AERATORS. 



A common system of cooling is to strain the milk into 

 the shipping cans, which are placed in a water tank just out- 

 side the stable, and to rely on the wind mill to keep the water 

 flowing. The milker is then supposed to give the milk a 

 stirring up every time he pours in a pail, either with a dipper 

 or one of the special hand stirrers or aerators of which I illus- 

 trate one in Fig. 86. 



It is a bell-shaped cup at the end of a rod. In pushing 

 it down through the milk it carries the air down and lets it 



