416 



CREAM. 



narrow limits 0-02 to 0-08 unless the milk be very dirty, when 

 it may even reach 0-15 ; in a sample where the last figure was 

 obtained the slime was brown and very gritty. 



It has been argued that the removal of the slime purifies the 

 milk to such an extent that its keeping qualities are enhanced. 

 This opinion is probably founded on observations of the number 

 of microbes contained in the slime ; but though a greater relative 

 quantity is found than in the milk, the numbers left in the 

 cream and separated milk are not diminished appreciably. 



Fig. 46. Diagrammatic Section of Separators. 



Practice has, however, shown that a mixture of cream and 

 separated milk in their original proportions keeps no better 

 than the milk from which they were separated. 



Micro-organisms are so small that their separation, unless 

 carried with much larger solid particles, would be almost im- 

 possible under the conditions of the separation of cream ; in 

 addition, many of them have a density less than that of milk 

 serum. 



The author found 



Top, . 



Middle, 

 Bottom, 



197,000 colonies per c.c. Growth on gelatine at 22 rapid, 



about 20 per cent, liquefied. 

 5,000 



194,000 



Growth on gelatine slow, none 

 liquefied. 



Attempts have been made to remove the impurities in milk 

 by nitration ; straining through a fine wire sieve and through 

 fine muslin or swansdown is always practised in dairies ; this 

 removes the grosser impurities i.e., hairs, large vegetable 

 fibres, etc. but the quantity removed in this way does not 



