EXPERIMENT WITH MAN. 177 



EXPERIMENT WITH MAN. 



Obviously with an apparatus constructed on this plan, the final test 

 of its practicability lies in an experiment with man. Since the comple- 

 tion of the new apparatus, 22 experiments with 5 different subjects, 

 covering a total of 60 days, have been conducted. These experiments 

 lasted from i to 13 days, during which time the subject remained 

 inclosed in the calorimeter chamber. Ordinarily the experiment lasts 

 3 or 4 days. In general, each experiment is preceded by a preliminary 

 period outside the chamber, during which the subject is given the special 

 diet to be tested, and his habits of life so modified as to conform with 

 those to be followed in the chamber. When the subject is to be engaged 

 in muscular work, he devotes considerable time in the preliminary days 

 to riding a bicycle in the open air, the amount of work performed being 

 as nearly as can be judged equivalent to that to be done later on the 

 bicycle ergometer inside the chamber. The food for the whole experi- 

 mental period, including the preliminary days, is carefully weighed, 

 sampled, and daily portions placed in proper containers ready for con- 

 sumption. The more easily decomposed materials, such as milk and 

 cream, are sampled, weighed, and analyzed each day. The bread and 

 meat when used are carefully sterilized in glass jars. The diet may be 

 so planned as to maintain a uniform quantity of nitrogen and a constant 

 calorific value from day to day. 



MEASUREMENT OF INTAKE AND OUTPUT OF MATERIAL. 



In experiments with man as carried out with this apparatus and 

 accessories, the following determinations of intake and output of ma- 

 terial are made : 



The intake consists of food, drink, and oxygen from respired air. 

 The amounts are determined by weighing. The analyses include de- 

 terminations of water, ash, nitrogen, carbon, hydrogen (organic), and 

 at times sulphur and phosphorus. The output of material consists of 

 products of respiration and perspiration, urine, and feces. The dry 

 matter of feces and urine is subjected to a series of analyses similar to 

 those for food, and the water and carbon dioxide of perspiration and 

 respiration are determined according to the methods discussed in this 

 report. The determinations of nitrogen in perspiration are made, when 

 necessary, according to methods given elsewhere. 1 



1 U. S. Dept. of Agr., Office of Experiment Stations, Bull. 136, pp. 52-53. 



12B 



