218 MODERN DAIRY PRACTICE. 



which may best be effected by lowering the milk-can into 

 hot water, while the milk is continually stirred by means 

 of a galvanized-iron rod supplied with a round disk. This 

 as well as the milk-can and skimmer must of course have 

 been thoroughly cleaned. 



At different places and at different seasons the milk 

 must be heated to a temperature of 77-95 F. (25-35 C.) 

 to become evenly sour in the course of eighteen to twenty 

 hours. The exact temperature required is determined by 

 experiment. When the correct temperature has been 

 reached, the milk-can is carefully placed, so that none of 

 the contents is spilled, into a barrel filled with hay. The 

 can should be covered with a clean cloth, on which a neat 

 hay mattress is put; the milk may now be left alone until 

 the next day. As soon as the work begins in the morning 

 the butter-maker should examine the starter, for the ripen- 

 ing process may be finished. This may conveniently be 

 done by placing the vessel in cold water when the milk 

 becomes evenly sour. In the majority of creameries it is 

 most convenient to have the acid ready at 8 to 10 A.M. 

 The upper inch layer of the milk is removed with a skim- 

 mer, as it sometimes is less palatable than the rest of the 

 acid. The starter is then mixed with the stirring-rod and 

 placed in cold water until used. 



The new starter does not usually taste as sour as the 

 buttermilk, and a somewhat larger quantity must there- 

 fore be used of it. As a disadvantage in the method may 

 be mentioned that the souring does not always progress in 

 the same manner, so that the butter on separate days of 

 even the same week may prove of different quality, while 

 an even quality of butter is easily gained by using a butter- 

 milk starter. 



