CHAPTER XXXI 

 THE SUPPLY OF PURE MILK 



IT is becoming more and more certain that the 

 character and quaHty of the actual things — the 

 natural products — which we use as food and accept as 

 " diet " are far more important matters in regard to 

 the preservation of health than had been until recently 

 supposed. There has been a tendency, resulting from 

 some of the well-ascertained chemical necessities of the 

 animal body and the equally well-ascertained chemical 

 composition of different articles of food, to suppose that 

 all that we have to do in regard to diet is to make 

 sure that our food supplies us with so much carbon, 

 hydrogen, nitrogen, and oxygen, with small quantities of 

 phosphates, sulphates, and chlorides of potassium, sodium, 

 calcium (lime), and iron, in a " digestible " form, in order 

 to replace those chemical elements as their combinations 

 are used up and thrown off as waste by our bodies. 

 The general notions current are little more exact than 

 this. It is recognized, it is true, that these elements 

 must be combined in certain forms ; that it is necessary 

 to take so much " proteid " (meat, gluten of flour, casein 

 of cheese and milk, albumen of egg), in which nitrogen 

 is a leading component, foods which are called flesh- 

 formers ; and, further, that it is necessary to take others 



which supply carbon and hydrogen but have no nitrogen, 



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