MILKING MACHINES. 9 



by the average dairyman will not satisfy requirements. The 

 complexity of the apparatus and the work involved in taking 

 the machine apart twice a day for cleaning and scalding, afford 

 an excuse for doing it but once a day, a practice which cannot 

 be too strongly condemned. Harrison has compared hand 

 milking with one of the earlier types of milking machine with 

 the result that the machine drawn milk was found to contain 

 from three to twenty times the number of bacteria found in 

 hand drawn milk (28). Stocking (62) has shown the infer-, 

 iority of machine drawn milk with the ordinary care given 

 machines. He paid particular attention to methods of cleaning 

 the rubber tubes, and by the exercise of elaborate precautions, 

 was able to produce results favorable to the machine. The 

 experiments show the possibility that the milking machine, in 

 the hands of an exceptionally careful dairyman, may decrease 

 the pollution of milk. Erf (20) made similar experiments 

 with the care of the rubber parts and in comparative tests of 

 the keeping quality was able to show results in favor of the 

 machine. Tests of milking machines usually have been con- 

 cerned chiefly with methods of caring for the rubber tubes used 

 with the machines. It has been found necessary to keep the 

 tubes in an antiseptic solution when not in use. Among the 

 substances that are permissible are brine, 3% formalin solution 

 or lime water prepared with an excess of fresh unslacked lime 

 (30). After use the tubes are rinsed in cold water, then with 

 hot water, and then immersed in the solution. If air remains 

 in any portion of the tubes, bacteria will multiply at that point. 

 Before use on the cow, the tubes must be thoroughly rinsed 

 with hot water to remove the antiseptic. If formalin is used 

 as an antiseptic there is always the possibility that it will not 

 be rinsed out thoroughly, either through carelessness or inten- 

 tion. On this account the use of this common milk preserv- 

 ative should be interdicted. The use of the milking machine 

 ought to lessen the danger from the contamination of milk by 

 the germs of infectious diseases of man, for it eliminates one 

 of the stages in milk handling during which persons come in 

 close contact with the milk. Nevertheless, there are many 

 other sources for possible infection of milk from diseased per- 



