186 ALIMENTATION. 



peculiar substance soluble in alcohol, called glutine, with fatty and inorganic 

 matters. The following is the composition of bread, according to Letheby : 



Nitrogenized matters 8'1 



Carbohydrates (chiefly starch) 51-0 



Fatty matters 1-6 



Saline matters 2-3 



Water 37'0 



100-0 



Potatoes. Potatoes are very useful as an article of diet, especially on 

 account of the agreeable form in which starchy matter is presented ; for they 

 contain but a small proportion of nitrogenized matter and do not possess as 

 much nutritive value as exists in bread. They are selected for description 

 from the vegetable foods for the reason that they are almost universally used 

 in civilized countries throughout the year. They are usually cooked thor- 

 oughly, but the raw potato is a valuable antiscorbutic. The following is the 

 composition of potato, according to Letheby : 



Nitrogenized matter 2'1 



Starchy matters 18'8 



Sugar 3-2 



Fat 0-2 



Saline matters 0-7 



Water . . 75-0 



100-0 



Milk. Milk, and articles prepared from milk, such as butter, cheese etc., 

 are important articles of food. In the treatment of disease, milk is frequently 

 used as a single article of diet. On account of the great variety of aliment- 

 ary matters which it contains, including a great number of inorganic salts 

 and even a small quantity of iron, milk will meet all the nutritive demands 

 of the system, probably for an indefinite time. It is largely used in the prep- 

 aration of other articles of food by cooking. Pure butter, which represents 

 the fatty constituents of milk, contains, in 100 parts, 30 parts of oleine, 68 

 parts of palmitine, and 2 parts of other fats peculiar to milk (Bromeis). 

 The following is the composition of cow's milk, according to Letheby : 



Nitrogenized matters 4*1 



Fatty matters 3-9 



Sugar 5-2 



Inorganic matters 0*8 



Water . . 86-0 



100-0 



In connection with the composition of human milk, to be given farther 

 on, the great variety of its constituents will be more fully considered. 



Eggs. As regards nutrition, the analogy between eggs and butter is evi- 

 dent when it is remembered that the constituents of eggs furnish materials 

 for the growth of the chick, to which must be added certain saline matters 



