THE SECRETION OF MILK. 41 



The air of the stable should be pure at the time of 

 milking, else the stream of milk will carry impurities 

 into the pail, and we shall then have a mechanical 

 mixture of clean milk and impure air, which is a 

 common cause of " tainted " milk. 



The milking is not completed until the milk from 

 each cow has been weighed daily, or at stated inter- 

 vals, and samples taken for testing the fat content. 



Milking machines have not been altogether suc- 

 cessful up to the present, but they are being perfected, 

 and we may soon expect to find a satisfactory 

 machine for milking cows placed upon the market. 

 Among those which have been more or less success- 

 ful are, Laval's Lactator, the Murchland, the Thistle 

 and the Lawrence & Kennedy. The last three are 

 Scotch machines. 



