536 MANUAL OF MILK PRODUCTS 



the freezer at 34 to 36, it may be frozen in eight to ten min- 

 utes and ample time allowed for whipping. 



The rate of the melting of the ice is governed in part by the 

 size of the salt and ice which are used. The proportions em- 

 ployed also affect the temperature of the freezing mixture. 



Another item of procedure usually neglected, especially by 

 small makers, is that of adding water to the salt and ice in order 

 to hasten the freezing process. When the ice and salt are dry, 

 a large part of the outer surface of the freezing can is exposed 

 simply to cool air, which, as is well known, is an exceedingly 

 poor conductor of heat. The heat contained in the cream can 

 be effectively withdrawn only at those points where an ice frag- 

 ment lies against the freezer can, here a spot and there a streak, 

 with air circulating between, until such time as there has accu- 

 mulated a sufficient amount of water from the melting of the 

 ice to form a close fitting conductor for the heat ; whereupon 

 the cream freezes promptly. Instead of starting to freeze the 

 cream at the temperature of 60 or 70, as is often recommended 

 (in cook books), in order that the ice may be melted to form 

 water, it is much better, if it is desired to hasten the freezing 

 process, to start with a colder cream and to pour a quart of 

 cold water around a gallon freezer, or some two gallons around 

 a ten-gallon freezer. This is especially true when a coarsely 

 broken ice is used. This is the reason that ice cream so often 

 freezes more quickly in summer than it does in winter. The 

 addition of water thus produces a brine of the temperature of 

 20 to 22. It is especially serviceable when snow is used in- 

 stead of ice. To secure the best all-round results, cream that is 

 put into the freezer at 60 to 65 should not be frozen in less 

 than twenty minutes, and it need not require more than twenty- 

 five ; if started at 45, from twelve to sixteen minutes are em- 

 ployed, while if at 34 to 35, it may be well and smoothly 

 frozen in eight to ten minutes ; in fact the conditions are more 

 favorable to success in the last than in the first instance. 



