May, 1929] SIMPLIFIED TECHNIQUE FOR MEASURING ENERGY 19 



The data on page 20 represent the total calories per 24 hours produced 

 by two different cows. If computed on basis of surface area, or to an equal 

 unit of live weight, the results would probably become even more uniform. 



Plate 4 — Apparatus for determination of percentage of carbon dioxide and oxygen in air 



The apparatus on left is for carbon dioxide only. This apparatus is provided with a 

 combustion tube in which methane gas can be split up by electric heat. The two ap- 

 paratus on right are duplicates which can be operated simultaneously by the motor- 

 driven rotating arm above. These two apparatus are for determination of carbon di- 

 oxide and oxygen. Note the large pryo capacity (black) which is sufficient to analvze 75 

 samples without replacing absorbent. 



The routine by which such results are obtained is as follows: - 



The animal is put into the respiration chamber and the doors are closed 

 at 4 P.M. At 4.15 P.M. the blowers are set in motion for a preliminary 



