CHAPTER XIII 

 THE USE OF PRESERVATIVES 



In early years the only means adopted for preserving 

 food were drying and cooling, both of which have been 

 known and used for many centuries. Within the last 

 fifty years other methods have been used for the same 

 purpose, and for some kinds of food they are far more 

 satisfactory and valuable than those just mentioned. The 

 iirst which we shall notice is the use of preservatives. 



The explanation of using preservatives is that it adds 

 £0 the food something which will check the growth of 

 microorganisms and thus prevent decay. Such preserv- 

 atives must fulfill two conditions : (i) They must have 

 some antiseptic power. (2) They must be comparatively 

 harmless to man. 



Poisonous Preservatives 



Since we know that the spoiling of food is due to the 

 growth of microorganisms it is easy to find chemical sub- 

 stances which will be perfect preservatives. If it were 

 simply a matter of protecting food from decay, it would 

 be the easiest thing in the world to bring about the 

 result. But it chances that most of the materials fatal 

 to the life and growth of microorganisms are also poison- 

 ous to man and therefore cannot be used in his foods. 



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