A method is described for estimating the volume of air in the lungs by the familiar principle of mixing this air with a measured volume of oxygen, and determining the extent to which the nitrogen of the pulmonary air is diluted. By employing a scrubber to remove carbon dioxide, and by measuring the volume of gas in the extrapulmonary part of the system at the end instead of the beginning of the respiratory period, it is possible to prolong the period to as many minutes as are necessary for complete mixture of the gases, and thereby to carry out the estimation without forced breathing. The determination can be carried out with the Roth-Benedict or Krogh spirometer, or, more economically, with the simple spirometer, shown in Fig. 1, assembled from ordinary laboratory equipment. The method gives the same results as the hydrogen method of Van Slyke and Binger (3), and obviates the use and analysis of hydrogen. The relative advantages of the two methods are discussed above. Dr. Ronald V. Christie has informed us that he has encountered considerable differences in the N2 content of the pulmonary air of different individuals. A gain in accuracy would therefore be made if this value were determined for each subject, and substituted for 79.1 in the calculation formulae.
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机译：描述了一种方法，该方法用于通过将空气与测量的氧气量混合并确定肺空气中的氮气被稀释的程度的熟悉原理估算肺中的空气量。通过使用洗涤器去除二氧化碳，并通过在系统末端而不是呼吸周期开始时测量系统肺外部分的气体量，可以将周期延长至气体完全混合，从而无需强制呼吸即可进行估算。可以使用Roth-Benedict或Krogh肺活量计进行测定，或者更经济地使用图1所示的简单肺活量计进行测定，该肺活量计由普通实验室设备组装而成。该方法的结果与Van Slyke和Binger（3）的氢方法相同，并且省去了氢的使用和分析。上面讨论了这两种方法的相对优势。罗纳德·克里斯蒂博士（Ronald V. Christie）告诉我们，他在不同个体的肺空气中的N2含量遇到了巨大差异。因此，如果为每个受试者确定该值，并在计算公式中替换为79.1，则可以提高准确性。
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