Preservation of Foods. 233 



at many drug stores. It costs from one dollar to one dol- 

 lar and a quarter per gallon. The preserving solution is 

 prepared by adding to nine parts of water that has been 

 boiled and allowed to cool, one part of the water glass 

 mixing the solution thoroughly. The eggs should be 

 placed in the solution within twenty-four hours after they 

 are laid. It is claimed that April, May and June eggs 

 keep better than do those laid later in the summer. It is 

 advisable to use July and August eggs first when eggs 

 from all of the months have been preserved. The eggs 

 should be examined before placing them in the solution 

 to see that they are clean and are not cracked. The stor- 

 age room should not be above 60 F. and should be as 

 uniform in temperature as possible. 



Preparation of vinegar. Fruit juices, as apple juice, 

 undergo a spontaneous fermentation. There are present 

 on the surface of the fruit, yeasts which find favorable 

 conditions for growth in the juice. These change the 

 sugar to alcohol as in the preparation of cider and wine. 

 If these liquids are allowed to stand exposed to the air, 

 they usually undergo, spontaneously, what is known as 

 the acetic fermentation in which, by the action of the 

 acetic acid bacteria, the alcohol is changed to acetic acid. 

 The bacteria causing this change are aerobic and grow 

 only on the surface of the liquid. It is therefore advisa- 

 ble to have the cask only partially filled with the liquid. 



The acetic bacteria grow most rapidly at 70 F. It re- 

 quires a number of months (12-18) to complete the proc- 

 ess of acetification. The process may be hastened some- 

 what by adding to the cider or wine a quantity of mother- 

 of- vinegar which is simply a mass of acetic acid bacteria. 

 After the process is completed the casks of vinegar should 

 be completely filled and stoppered tightly in order to pre- 



