Nov., 1931] FOODS IN A COLLEGE COMMUNITY 



13 



TO DRAIN 



Fig. 2. A simple form of oxy-calorimeter. 



A, combustion chamber; c, tube conducting air from base of com- 

 bustion chamber into soda-hme container, B; C, blower; b, rubber bath- 

 ing-cap with button, e; H, upright with cross arm supporting phite, d; 

 E, 2-hole stopper through which pass the two ends of the copper cool- 

 ing coil; V, valve to control entrance of water or air into cooling coil; 

 O2, petcock through which oxygen is introduced into the apparatus. 



The can is filled with oxygen a second time, the rubber cork is replaced 

 in the tee, and the blower is set in motion. When equilibrium is estab- 

 lished, that is, when the button, e, on the bathing-cap just comes in con- 

 tact with the plate, d, the food substance is ignited. 



To cool the can a supply of cold water, either from the tap in 

 winter-time or from a reservoir containing ice water, is allowed to flow 

 into the copper coil embedded in the soda-lime. The amount of water 

 passing through this coil can be controlled b}' a pinchcock, but at the 

 beginning of the combustion the apparatus is brought into equilibrium 

 by running the blower without having any cold water in the cooling 

 pipe. As a result of the electrical ignition, there is momentarily a con- 

 siderable expansion of the air in the system by the heat developed. Pro- 

 vision must, accordingly, be made to avoid undue distention of the rub- 

 ber cap during the combustion. At the beginning of the experiment, 

 therefore, when the apparatus has been brought into temperature equi- 

 librium and the rubber bathing-cap is distended so that the button, e, 

 just comes in contact with the plate, d, a pump (which is used subse- 

 quently to measure the oxygen consumption) is connected to the pet- 



