NUTRITION LABORATORY. 223 



of a variety of extra foods, such as crackers, chocolate, and particularly 

 the products of the American soda fountain. It is planned to include 

 in this study a considerable number of noonday lunches and certain 

 bottled beverages. In this research Mrs. Benedict has been very intel- 

 Ugently assisted by Miss Marion L. Baker. A first report of this inves- 

 tigation has already been made and is reviewed in subsequent pages. 



Comparison of respiration apparatus and breathing appliances for 

 human subjects. — The development of the portable respiration appa- 

 ratus noted elsewhere and the appHcation of a half -face mask for res- 

 piratory exchange work offered an opportunity to Dr. T. M. Car- 

 penter for an elaboration of his comparative studies of the respiratory 

 exchange obtained with various breathing appHances and respiration 

 apparatus. In addition, the question of the use of entirely untrained 

 subjects was for the first time adequately studied. A series of com- 

 parisons of the respiratory exchange was obtained with 17 first-year 

 medical students who had never had a breathing apphance attached 

 to them. The portable respiration apparatus and a respiratory- valve 

 apparatus (so-called Tissot) were used. The breathing appliances 

 were the Denayrouse mouthpiece, the nosepieces devised by Benedict, 

 and the Siebe-Gorman half-face mask. The measurements of the 

 respiratory exchange were made in 10 to 15 minute periods, when the 

 subjects were in the post-absorptive condition. The periods were so 

 arranged that there was alternation between the two respiration 

 apparatus and alternation between the breathing appliances. Twelve 

 periods were made with each subject, and thus there was a duphcate 

 with each breathing appliance with each respiration apparatus. 

 Measurements were made of the carbon-dioxide elimination, oxygen 

 absorption, pulse-rate, respiration-rate, and volume of lung ventilation 

 per minute. The respiratory quotient and the volume per respiration 

 were calculated; with the respiratory- valve apparatus the composition 

 of the expired air was also determined. 



The study showed that accurate results can be obtained with the 

 majority of untrained, presumably healthy subjects, provided at least 

 three periods on one day are made; that there is very little choice, if 

 any, in the breathing appliance to be used, and that it depends mainly 

 upon the preference and comfort of the subject; that both the portable 

 apparatus and respiratory-valve apparatus give strictly comparable 

 results for oxygen absorption and that the simplest, quickest, and 

 most efficient method of determining the oxygen consumption of a sub- 

 ject at rest is by means of the portable respiration apparatus. The 

 carbon-dioxide elimination as determined by the portable apparatus 

 is slightly higher; consequently the respiratory quotient is higher than 

 that determined by the respiratory-valve apparatus, this being due 

 primarily to the greater volume of lung ventilation per minute with the 

 portable respiration apparatus than with the respiratory-valve appa- 



