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SCIENCE 



[N. S. Vol. XLIII. No. 1108 



effectively " the high cost of living." It is 

 altogether probable also that during the next 

 few years determinations of the respiratory 

 exchange will be extensively introduced into 

 routine clinical use. 



For these reasons there is a special timeli- 

 ness in the thorough study of the principal 

 methods now in use for the determination of 

 the respiratory exchange in man, offered by 

 Carpenter in the first of the publications 

 above listed. 



In general such methods fall into two 

 classes : those involving a closed circuit on the 

 Regnault-Eeiset plan, and those involving a 

 so-called open circulation. As the most com- 

 plete working out of the closed circuit method 

 the apparatus devised by Benedict has been 

 especially studied in its various forms in the 

 work before us. With the results so obtained 

 Carpenter has compared particularly as ex- 

 amples of the open circulation the Zuntz- 

 Geppert method and the method of Tissot, of 

 which that of Douglas is a modification. 



In all forms of the Benedict apparatus the 

 subject continually rebreathes from a closed 

 system of chambers, pipes and absorbers in 

 which the air is kept in circulation by a 

 blower. The total carbon dioxide exhaled is 

 absorbed and weighed; and the total amount 

 of oxygen required to replace that absorbed by 

 the subject from the system is determined 

 either by weight or volimie. 



In the Zuntz-Geppert method the subject 

 inspires the outside air through valves and a 

 mouthpiece, and expires through a meter con- 

 nected with a sampling device. From the 

 meter reading and the analysis of the samples 

 the total oxygen absorbed and carbon dioxide 

 exhaled are calculated. 



In the Tissot method the subject also in- 

 spires outside air, but expires into a carefully 

 counterbalanced and graduated spirometer, 

 from which a sample is later taken and 

 analyzed. 



In the Douglas method the expired air is 

 caught in a bag from which it is later forced 

 through a meter: the respiratory exchange 

 being determined by the meter reading and 

 the analysis of a sample. 



Carpenter finds that with care and skill 

 practically equivalent results are obtainable 

 with the Benedict, Zuntz-Geppert, and Tissot 

 methods. With the Douglas bag the discrep- 

 ancies are slightly greater, although in this 

 case also inconsiderable. 



Although Carpenter reaches no positive con- 

 clusion as to the superiority of the features of 

 any one of the general methods above de- 

 scribed, he does point out that the ability of 

 the investigator to perform accurate gas anal- 

 yses is of special importance; and that apart 

 from the gas analyses the Benedict method is 

 more complicated than the Zimtz-Geppert, 

 Tissot or Douglas methods. He especially 

 emphasizes the fact that for purposes of gas 

 analysis the apparatus of Haldane is by far 

 the most perfect yet devised. He makes the 

 excellent suggestion that as a check upon the 

 accuracy of the experimental data analyses of 

 pure air also should always be made and re- 

 ported. 



The reviewer leaves this work with a strong 

 impression, although perhaps Carpenter him- 

 self would disclaim any intention of creating 

 it, that the best method now available consists 

 in the use of a spirometer of the Tissot type 

 (or for special piu-poses a Douglas bag) and a 

 Haldane analyzer. Great as have been the 

 contributions of the Benedict apparatus, it ap- 

 pears inferior to this form of the open cir- 

 cuit, alike in theory, in the complexity of its 

 manipulation, and in the cost of installation. 



In " Energy Transformations during Hori- 

 zontal Walking " Benedict and Murschauser 

 describe the results obtained from a man walk- 

 ing upon a treadmill driven at various rates 

 of speed. The energy expenditure of the sub- 

 ject in a post-digestive condition, standing 

 absolutely still, is first determined. By sub- 

 tracting this basal value from the figures ob- 

 tained during walking they compute the extra 

 energy expended in moving the body per kilo- 

 gram and horizontal meter. For slow paces 

 a distinctly uniform figure is obtained. This 

 increases, however, with rapid walking, a point 

 being reached at which the energy expenditure 

 of running is less than that of rapid walking. 

 It is shown that the high rate of energy ex- 



