CLEANSING OF UTENSILS. 13 



ture offers the best conditions for milking, as regards the con- 

 tamination from air. 



Cleansing: of utensils. The proper care of the vessels with 

 which milk comes in contact is an important factor in reducing 

 contamination. No precaution for producing good milk is 

 more easily carried out, yet none is more generally neglected. 

 Rinsing in cold or lukewarm water is necessary first to remove 

 the milk. If hot water is used at first it will render cleaning 

 difficult by causing some of the milk constituents to adhere to 

 the utensils. This preliminary step is followed by scrubbing 

 with hot water containing soap powder or some alkali (16, 58), 

 and this in turn by rinsing in hot water. The practice of 

 merely rinsing utensils without washing and scalding, after 

 the night's milking, and then using them the next morning, is 

 intolerable. 



Scalding. Too often, the final rinsing in hot water is con- 

 sidered sufficient. Bacteriological requirements, however, 

 demand the more thorough application of heat. Harrison (28) 

 and Russell (50) have shown the inefficiency of the ordinary 

 haphazard scalding. To insure complete destruction of all bac- 

 teria, that is, sterilization, requires that the utensils be sub- 

 jected to steam under pressure of at least five pounds for twenty 

 minutes. Fig. 4 shows the apparatus used for this purpose, 

 containing a car used for milk bottles. This method of heating 

 utensils is the only one that may properly be designated as ster- 

 ilization. The others do not sterilize, as they do not result in 

 the death of all the spores of bacteria. Very excellent results 

 may be obtained by subjecting the utensils to the action of steam 

 in a closed chamber, but not under pressure. La Grange (38) 

 tested the effectiveness of such a piece of apparatus, finding that 

 99.2% of all bacteria in milk bottles were killed . Those surviv- 

 ing were spore-bearing organisms. To obtain this result the 

 steam was admitted to the room for fifty-five minutes, about 

 .half of this period having elapsed before the temperature reached 

 the boiling point. It is the more common practice to scald 

 utensils over a jet of steam, one by one. La Grange used steam 

 from a half -inch pipe, under a pressure of thirty pounds, and 

 with a duration of fifteen seconds obtained results as satisfac- 



