FOOD. 125 



completely nutritious, and of the most uniform composition. For the 

 continued maintenance of health and strength in a working condition, 

 other articles, such as fresh vegetables, sugar, milk, fruit, etc., should 

 be mingled with the above, in a variety of proportions ; but there is no 

 doubt that bread and fresh meat, with a certain quantity of fat, will 

 prove sufficient for the wants of the system, for a longer time than any 

 other single articles of food. 



Such a diet also affords the best means of ascertaining the absolute 

 and relative quantities of the different proximate principles required for 

 food. If we take the average composition of meat and bread, and esti- 

 mate the quantities of their solid albuminous, starchy, and saline ingre- 

 dients, together with the water contained in both solid and liquid food, 

 we find that the daily ration is composed nearly as follows : 



Albuminous matter 130 grammes. 



Starch and sugar 300 " 



Fat 100 " 



Mineral salts 20 " 



Water . .' 2000 " 



Of the mineral salts, nearly eight grammes are naturally contained in 

 the substances used for food and drink ; the remainder consists of sodium 

 chloride, artificially added to the food, or used in its preparation. 



The proportion in which the albuminous and the non-nitrogenous 

 principles should be mingled in the food is of considerable importance, 

 and this proportion has been determined within very accurate limits. 

 In making such an estimate it is necessary to include the carbohydrates 

 (starch and sugar) and the fats under the same head ; but the fats are 

 properly regarded by all writers as having a different alimentary value 

 from the carbohydrates. This depends upon the well-known fact that 

 the final result of the transformation in the living body of all the non- 

 nitrogenous substances is carbonic acid and water, thus representing a 

 process of oxidation, the necessary oxygen being introduced with the 

 inspired air. But the capacity for oxidation of the fats is greater than 

 that of the carbohydrates, as shown by the relative proportion by weight 

 of their constituent elements. 



. . . f C 72 C 44.47 



The composition, by weight, 1 , . ** TT / 



of starch (C 6 H 10 5 ) is } * 80 "' " P ' 04936 



162 100.00 



Here the oxygen is already present in sufficient proportion to saturate 

 all the hydrogen by the formation of water; while the 44.47 parts of 

 carbon will unite with 118.58 parts of oxygen to form carbonic acid. 



On the other hand, if we take palmitine as representing the average 

 constitution of the fats, we have 



The composition, by weight, ( 612 C 75 ' 93 



offat(C 51 H 98 6 )is {* 9 9 * -, in 100 parts, H 12.15 



806 100.00 



