44 MII.K AND TTS PRODUCTS AS POODS 



mechamcal use will be made of cliemislry as an aid in deter- 

 mining the \'alues of the (HHerent loodstulfs and how they may 

 best be combined with each (jther in the compounding of more 

 economical and complete rations and diets on which animals and 

 man will grow and thrive. At times the biological study of food- 

 stuffs may move in ad\'ance of chemistry, as it has already done 

 in discovering the presence in milk-fat of a fat-like or fat-soluble 

 substance, as yet unidentified, which renders this fat altogether 

 superior to other animal anfl vegetable fats lacking this growth 

 and health-promoting foodstuff. It is the prcjvince of chemistry 

 to ascertain, if possible, what this substance is. The same ma}' 

 be said of a water-soluble substance which is not nearly so limited 

 as to its sources, being present in sufficient quantit}' in cereal 

 grains and most of the mixed diets. 



CHEMICAL CLASSIFICATION 01' MILK AND ITS PRODUCTS 



AS FOOJJS 



From the chemical standpoint, the constituents of the food 

 material consumed by animals and man are classified under the 

 heads of water, combustible matter and ash, mineral matter or 

 salts — all three terms being applied to the last class. 



The combustible matter includes the carbohydrates (such as 

 starches and .sugars), the fats (such as milk-fat. oli^'e oil and 

 other plant oils, and meat-fat), and the proteins (such as the curd 

 of milk, the gluten of wheat and the muscle fiber of lean meat). 



The carbohydrates and fats arc largely burned to supply 

 heat and energy, and are also used for the making of fat in the 

 body and in milk. 



The proteins are used, in part, for the same ]iurposes as the 

 carbohydrates and fats, but their distinct function, which these 

 latter cannot perform, is that of supplying material for the 

 making of muscle and other body tissue, and the protein of milk. 



The ash or mineral matter is used for making bone, regulating 

 the heart action and the elasticity of the muscles in general, and 

 preventing acidity of the bloofl and tissues. 



Under the older classification of foods we tnid that milk 



