FOOD 



123 



82. Fuel Value of Foods. Since two of the nutrients 

 are used entirely for the production of heat in the body, 

 and since the other one is often used in a large quantity 

 for the same purpose, the fuel value of foods is determined 

 by finding how much heat they will produce when oxi- 

 dized or burned. In order to determine the fuel value 

 of foods it is necessary to burn them in an apparatus 

 known as the bomb cal- 

 orimeter. This is a very 

 simple instrument com- 

 posed of an inner and 

 outer chamber 

 with a space be- 

 tween for water. 

 The food to be 

 burned is placed 

 in the inner 

 chamber and a 

 thermometer is 

 placed in the 

 water between 

 the inner and 

 outer chamber. 



The temperature of the water is taken. After the food 

 is burned the temperature of the water is again taken. 

 The weight of the water and of the food in the calo- 

 rimeter must be known. The increase in temperature 

 multiplied by the weight of the water in grams will be 

 the amount of heat produced by the quantity of food 

 burned. 



The food calorie is larger than the ordinary or common 

 calorie. The food calorie may be defined as the quantity 

 of heat necessary to raise the temperature of one kilogram 



BOMB CALORIMETER FOR DETERMINING THE 

 FUEL VALUE OF FOOD 



F is the food chamber; W is the water for re- 

 ceiving the heat from the burning food; P is 

 packing to prevent the loss of heat; V is the 

 entrance valve; T is a thermometer; O is the 

 tank for supplying oxygen. 



