Digestion — Respiration — Calorimetry — Energy. 47 



of 171.8 lbs. of food, water, and oxygen it stored up matter as 

 follows : 



Grams Pounds 



Proteins or dry lean meat 219 * 0.48 



Fat 281 0.61 



Mineral matter 10 0.02 



Water 525 1.17 



Total 1,035 2.28 



It has been shown that the intake of the body of the ox during 

 the day of the trial exceeded the outgo by 2.30 lbs. The table ac- 

 counts for practically all of this in the 2.28 lbs. of increase here 

 reported. 



The 0.02 lb. of mineral matter must have largely gone to increase 

 the bony structure. Fresh lean meat is nearly two-thirds water, 

 therefore the 0.48 lb. of dry lean meat equaled about 1.25 lbs. of 

 fresh lean meat. The fatty tissues of the fattening ox are about 

 two-thirds fat, hence the ox put on slightly less than 1 lb. of body 

 fat during the day. 



Thus we are shown that a 1570-lb. ox confined in a respiration 

 chamber for 24 hours consumed during that time 11 lbs, of clover 

 hay, 13.2 lbs. of oat straw, 8.2 lbs. of bean meal, and 2.13 oz. of 

 salt; drank 123.7 lbs. of water; and breathed in 16 lbs. of oxygen 

 gas. From all this it gained 2.28 lbs. of body weight, of which 

 about 1.11 lbs. was dry lean meat, fat, and mineral matter, and 1.17 

 lbs., or over one-half, was water. 



III. Calorimetry. 



In nutrition studies it is helpful to consider food according to its 

 power to produce heat. Such studies fall under the head of calo- 

 rimetry. 



68. Calorimetry. — The calorimeter is an apparatus in which a 

 given quantity of material is burned with pure oxygen gas under 

 pressure, the heat evolved being taken up by water and measured 

 with a thermometer. 



A Calorie is the amount of heat required to raise 1 kilogram of 

 water 1° C, or 1 lb. of water 4° F. 



A therm is 1000 Calories, or the amount of heat required to raise 

 1000 lbs. of water 4° F. 



