90 BENEDICT AND JOHNSON— ENERGY LOSS OF 



not inconsiderable factor in the muscular activity of most women, 

 exact information as to the energy needs for the performance of the 

 domestic duties of the household is essential for an intelligent com- 

 putation of the daily requirements of the average woman. These 

 domestic activities consist for the most part of sitting, standing, 

 walking, sewing, sweeping, dusting, washing clothes and dishes, iron- 

 ing, cooking, bed making, etc. What, then, are the requirements for 

 energy above the basal for these and other activities? 



The Nutrition Laboratory, in establishing its long series of basal 

 values for new-born infants, children, and adults, has adhered to the 

 time-consuming method of studying individuals, and a decade has 

 been needed to secure this basal information. In the belief that with 

 definitely established basal values, the excess energy required for 

 muscular activity could be studied to greater advantage with groups, 

 and thus general average values be obtained more rapidly and pos- 

 sibly with a greater degree of accuracy, a respiration chamber of 

 sufficient size to seat 30 to 40 persons was constructed and its ac- 

 curacy tested.^ 



This respiration chamber, 5.18 meters long, 3.81 meters wide, 

 and 2.29 meters high, is well ventilated by forcing outdoor air in 

 at one end and withdrawing the chamber air at the other. The 

 special feature of this apparatus is the sampling device. A rotary 

 air impeller discharges air from the chamber into a copper box or 

 wind chest having three circular openings in it, two of these being 

 10 millimeters in diameter and one 29 millimeters in diameter. The 

 amount of air leaving the wind chest through these three openings 

 is roughly proportional to the area of each opening and is obviously 

 alike for the lo-millimeter openings. Over each of these two open- 

 ings is placed a can covered with a rubber bathing cap to enclose the 

 discharged air. By means of a supplementary blower, air is with- 

 drawn from each of the sampling cans at exactly the rate at which 

 it is delivered into the can. In actual practice, therefore, the air 

 enters the cans at atmospheric pressure, is immediately withdrawn, 

 forced through containers holding sulphuric acid and soda lime, 

 respectively, and then discharged. By weighing the soda-lime con- 



1 For a detailed description of this chamber, see Benedict, Miles, Roth, 

 and Smith, Carnegie Inst. Wash. Pub. No. 280, 1919, pp. 92 to 119, inclusive. 



