78 BRITISH DAIRYING. 



the odours which it contains disperse into the air. Cold air 

 coming in contact with the surface of warm milk expands, and 

 therefore rises by virtue of its diminished gravity : its capacity 

 for holding gases, vapours, odours in suspension, is increased, 

 so that it takes up the volatile odours of the milk, and may 

 even be made to purify it to some extent of its " cowey ;) smell, 

 particularly when the milk is well stirred about for a time. All 

 this needs only to be mentioned to enable dairymaids to recol- 

 lect that it is so, and that the truth of it may be tested without 

 much trouble by almost anybody. 



In order to ascertain which cows, if any, are not worth 

 keeping for milk, each one's milk should be weighed when it is 

 taken. The quantity is quickly seen by using the spring 

 balance shewn in Fig. 15, which is sold by The Dairy Supply 

 Co., and called the " Sandringham Milk Recorder." The 

 quality of each cow's milk can be ascertained by the apparatus 

 seen in Fig. 24, page in. 



Temperature and Milk. 



But if cool milk be placed at rest in a warm room the air of 

 which is not pure and fresh, the moisture which the air contains 

 condenses on the surface of the milk, and with it the odour of 

 the room is also deposited. Hence it follows that milk is not 

 so easily contaminated in this way as might have been supposed, 

 so long as it is warmer than the air which rests upon it. The 

 odours of the shippon, the breath of the cows, the keen smell 

 of silage, the sickening stench of a liquid manure tank, or of 

 a piggery, are comparatively harmless so long as the milk 

 remains warmer than the air in which these odours float. 

 When milk is taken from the cows' udders it is at a tempe- 

 rature of 98 or less ; and as the air is but seldom at that 

 high temperature, even inside a cowshed in the heat of summer, 

 the milk will take but little harm from the absorption of odours 

 until its own temperature has fallen to that of the air. That this 

 is so is very fortunate ; otherwise milk would be commonly 

 tainted during the process of milking. All the s; : me, however, 

 it should be taken at once to the cool retreat of the dairy, and 



