248 CARNEGIE INSTITUTION OF WASHINGTON. 



COMPARISON OF METHODS FOR DETERMINING THE RESPIRATORY EXCHANGE. 



This research has been continued by Mr. T.M. Carpenter during the 

 past year. The accuracy of the determination of the carbon-dioxide 

 ehmination in experiments on respiratory exchange by the Tissot 

 and Zuntz-Geppert methods has been checked by introducing known 

 amounts of carbon dioxide into the air-current of an artificial res- 

 piration apparatus. The necessity of using the dehcate automatic 

 counterpoise of the Tissot spirometer has been studied. 



The practicabihty of the Mueller water-valves for separating 

 inspired and expired air has been tested by running comparative 

 experiments on the respiratory exchange, using other tested valves 

 in the same series. 



A method for determining the back-leak through respiration valves 

 has been devised and employed in testing the various types of valves. 

 The effect on the respiratory exchange of varying the speed of the 

 circulating air-current in the Benedict respiration apparatus has 

 been determined in comparative series of respiration experiments. 

 Several series of control tests on the water absorbers, the ventilation 

 measurer, and the 1 -liter Bohr meter have also been carried out in 

 connection with the use of the Benedict respiration apparatus. 



The possibility of substituting stick yellow phosphorus for potas- 

 sium pyrogallate has been thoroughly tested with both forms of the 

 Haldane gas-analysis apparatus. 



METABOLISM OF INFANTS. 



In studying the metabolism of pathological infants, the same 

 difficulty has been found as was observed in the studies with dia- 

 betics, namely, the lack of adequate normal values for comparison. 

 In order to accumulate data with regard to the metabolism of normal 

 infants of different ages, weights, and sex, a respiration apparatus 

 giving determinations of both the carbon dioxide and oxygen was set 

 up at the Massachusetts General Hospital and Miss Alice Johnson, 

 of the laboratory staff, was placed in charge. With the cooperation 

 of Dr. Fritz B. Talbot, an extensive series of experiments was carried 

 out on normal infants varying in age from a few days to several 

 months. Carefully selected periods of complete muscular rest were 

 secured with practically all of the subjects, thus furnishing an excel- 

 lent base-line for the discussion of the normal metabolism of infants. 



THE NORMAL METABOLISM OF MEN AND WOMEN. 



In connection with the numerous researches in metabolism carried 

 on in the Nutrition Laboratory, data with regard to the metabolism 

 of normal men are rapidly accumulating, but the use of women sub- 

 jects is precluded in most experiments and hence a special research 



