76 SCIENCE AND PRACTICE OF DAIRYING. 



(3) Only sweet milk, which remains unchanged at ordinary 

 temperatures, for some time after sale, without becoming coagulated, 

 and which stands boiling, should be provided. 



(4) The milk should be worth its price, that is to say, it should 

 have the average percentage of total solids and fat, found in the 

 milk which is obtained in the respective districts, from properly-fed 

 and well-tended cows. 



(5) Only milk which comes from healthy cows, free from foreign 

 ingredients, and uncontaminated with pathogenic germs, should be 

 sold. 



The milk of cows which have had fever, or have been treated internally 

 or externally with medicines, is unsuitable for sale. Care ought also to 

 be taken that the milk is kept clear of contact with people suffering from 

 infectious diseases, or people having charge of such persons. 



The stringent demands which we are justified in making at 

 present on the milk-trade, and which in some places are beginning to 

 be timorously enforced, will become more easily and more perfectly 

 granted the more the milk-trade is concentrated. The supervision 

 of the sale of milk is uncommonly difficult in towns in which the 

 sale of half -milk, that is, a mixture of creamed evening milk with 

 whole morning milk, is practised. 



In addition to milk, cream, skim -milk, butter-milk, and whey 

 are sold in commerce. 



Cream, as it is usually sold, contains from 11 to 25 per cent of fat; 

 but the want of definite regulations concerning its sale has never been 

 felt. The same may be said with regard to butter-milk and whey, which 

 only come into the market in small quantities. With regard to the super- 

 vision of the trade in skim-milk, where it is desired, the tests should be 

 limited to its appearance, smell, and flavour, and to ascertain whether ii 

 stands boiling, and is free from unusual properties. The determination 

 of the specific gravity (which in the case of skim-milk obtained from 

 centrifugal machines generally containing not more than '5 per cent of fat, 

 varies between T0335 and 1-0360) will reveal the addition of any large 

 quantity of water. Since the high value which skim-milk possesses as a 

 nutritive food depends entirely on its percentage of albuminous matter, it 

 is quite immaterial whether it contains a tenth of a per cent of fat more 

 or less ; and for this reason it is quite wrong to prevent its sale unless it 

 has been proved to contain a certain percentage of fat. 



The analysis and testing of skim-milk is carried out very much 



