VINEGAR AS A PRESERVATIVE 185 



The flavor is much changed, and too large a quantity of 

 salt meat is not wholesome. Moreover, salt somewhat 

 changes the physical nature of food, so that it is not quite 

 so easily digested. Salt foods, therefore, cannot wholly 

 take the place of fresh foods. This is especially true since 

 they are lacking in the vitamin which prevents scurvy, 

 a trouble frequently met with among sailors who have 

 subsisted too largely upon salt foods. Nevertheless such 

 foods are very useful, and if a sufficient quantity of fresh 

 food (or even powdered lemon, as used by recent polar 

 expeditions) is consvuned with them they may be used 

 very advantageously as part of our diet. In preparing 

 such foods for the table they should be soaked in water to 

 remove as much of the salt as possible. 



Vinegar. Acetic acid is another material used legiti- 

 mately for the preservation of certain kinds of food prod- 

 ucts. In its best known form, vinegar, it is the basis of 

 the preservation of all kinds of pickles. The acetic acid 

 in these cases serves two purposes : (i) It gives a new 

 flavor to the material, rendering it very sour. (2) It pro- 

 tects the product almost totally from the action of bacteria. 

 The pickling of cvtcumbers has become a great industry, 

 green cucumbers being more extensively used for the pur- 

 pose than any other material. The vinegar is frequently 

 mixed with spices, both for the purpose of added flavor 

 and to aid in the preservation. Although pickled vegetables 

 keep well, they do not keep indefinitely. Pickle brine 

 sometimes becomes covered with a scum composed of bac- 

 teria, and the pickles themselves may grow soft from decay... 

 If the pickles are taken out and boiled for a few minutes,, 

 the microorganisms will be destroyed, the trouble may 



