52 THE COMMON SENSE OF THE MILK QUESTION 



We may divide food into four great classes, as 

 follows: (1) protein, sometimes called proteid, or al- 

 buminoids; (2) fat; (3) carbohydrates; (4) mineral 

 matter, usually called ash or salts.' In addition to 

 these, water is a very important ingredient of food, 

 entering as it does into the composition of every 

 part of the body, the bones even containing more 

 than 10 per cent of water.' It follows, therefore, 

 that the large percentage of water contained in all 

 kinds of milk is not wholly waste and without nutrient 

 value. Protein is the muscle-building element and 

 is of prime importance, as the word itself indicates.* 

 It contains carbon, hydrogen, oxygen, and nitrogen 

 and, generally, but not always, sulphur. Sometimes 

 there is found in addition to these phosphorus and 

 iron. Fat, as most people know, is composed of 

 carbon, hydrogen, and oxygen only. Carbohydrates 

 is the name given to a compound of hydrated carbon. 

 The carbon is compounded with hydrogen and oxygen 

 in the proportion of two to one, the proportion in 

 which these two elements combine to form water. 

 All the glucoses and sugars are carbohydrates, there- 

 fore the sugar in milk, which differs from cane sugar 

 very materially, belongs to that class. The mineral 

 matter in milk, the salts or ash, is principally useful 

 in building and hardening bone. This is by no means 

 a very complete or exact analysis of food elements, 

 * Protein = I take the fltst place.. 



