THE FREEZING OF ICE CREAM 377 



the while. A teaspoonful of any table gelatin dissolved in half 

 a cup of water will suffice for a gallon of ice cream. 



Gum tragacanth, a vegetable gum, is used but is not as 

 strong to prevent crystallization as gelatin and is more used to 

 dry out the mix, to produce a compact meaty mass. This is 

 used in the form of a dry powder, preferably mixed with finely 

 powdered sugar to aid distribution. 



The freezing of ice cream is an easy matter provided too 

 much sugar has not been used. Water freezes at 32 degrees F., 

 milk and cream at 31 degrees, and cream in which 14 per cent 

 sugar has been dissolved, at 28 degrees. If more sugar be 

 added the freezing temperature will be yet more depressed. 

 Water-ice and sherbets freeze with more difficulty than ice 

 creams because carrying more sugar. 



The best simple trick in the matter of quick and easy freez- 

 ing is to pour cold water in among the ice lumps and salt grains 

 before starting to turn (Fig. 123). 



When the mix is in the freezer can and all is adjusted, cracked 

 ice should be added to the freezer tub first, until about one-third 

 full, salt is then scattered over the ice, more ice is then added 

 to fill the tub nearly full, and salt again scattered on top of the 

 ice. The ice should not be packed about the can. At this point 

 in the process the cold water is added until it flows out the 

 safety hole on the side. The first thing noticed as a result of 

 adding the water is that it will turn much easier than without it, 

 and second, it will freeze in a fraction of the time often re- 

 quired in the dry ice-salt method. Moreover, since the mix is 

 comparatively warm when added and must be cooled to about 

 30 to 29 degrees before the swell can take place, it is useless to 

 turn rapidly at first. Butter lumps are formed by turning too 

 fast at first and churning it. The freezing process may 

 even be done on time schedule. During the first seven minutes 

 after the water has been added the freezer crank should be 

 turned rapidly, two or three revolutions, every half-minute to 

 keep the walls clear and prevent the dasher from setting. After 

 seven minutes of cooling the mix will be nearly ready to freeze 

 and will be cool enough to be viscid. In this condition it will 



