182 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



tion in regard to cleanliness being noted. Cement is the 

 best material because it can be most readily cleaned, but 

 smooth boards with tight joints, oiled or painted, will 

 do fairly well for the walls and ceiling, although it is 

 desirable to have the walls finished in cement for about 

 four feet above the floor, especially in the room used 

 for washing the milk vessels and utensils. The floor 

 should always be constructed of cement. The lighting 

 should also be observed. There should be a sufficient 

 number of windows to furnish good light, and some good 

 method of artificial lighting is also desirable. All win- 

 dows and doors should be screened against flies. 



3. Apparatus. The apparatus present in the milk 

 house and its condition should be observed. There ought 

 to be some means of cooling the milk and keeping it 

 cool, and there should be facilities for cleaning the milk 

 vessels and utensils, including a convenient and plenti- 

 ful supply of hot and cold water. If the milk is bottled, 

 a bottle washer, bottle filler, and bottle capper should 

 be provided. These need not necessarily be expensive. 

 A sterilizer is also desirable. It is a protection against 

 the contamination of the milk through returned bottles 

 and it is also a great aid in keeping the milk vessels and 

 utensils clean. A bottle filler and capper will guard 

 the milk against contamination by the fingers. 



A cooler, sometimes called an aerator, is necessary 

 for the rapid cooling of milk. This apparatus is con- 

 structed so that the milk flows in a thin layer over a 

 sheet of tinned metal while cold water or brine flows 

 on the other side of the metallic sheet and absorbs heat 

 from the milk. There are four types of milk coolers: 

 (a) conical, ( b) corrugated, (c) tubular, and (d) inter- 

 nal or double-tube. 



