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592 HEINZ SPECHT forced to recede from the wick in order to carry a sufficient quantity of oxy? to the flame front. Not only is vaporization of the fuel of the candle flr progressively inhibited, but also the flame literally blows itself out. It;l however, been possible to maintain hydrogen flames in air at altitudes some in excess of that for the candle flame since combustion of hydrogen is notfl pendent on the melting and vaporization of the fuel by the heat of the flameii While relatively few data are at hand to indicate the quantitative effect' increasing atmospheric pressure on the metabolism of living systems, effecif. oxygen and carbon dioxide at high pressure30 indicate that marked influendl ; metabolism do occur. 1. Oxygen and Carbon Dioxide The pressure-labile chemical combination of oxygen and carbon dioxide the blood is a reciprocal relation involving the binding power of hemoglfL 10 20 30 40 50 60 70 SO 90 100 HO pOs.mm. Hg Figure 4. Oxygen dissociation curves of blood Figure 5. Carbon dioxide dissociatidtt, of a man at work." of blood of a man at work.",$| and bases in the blood complex for these two gases of the atmosphere.iEssint thbre iraSlnyolved' chemicar redistribution" oflbns-Eetween blopd.;.pl;a~ tissue solutes31 for every change in partial pressure of the constitueiS^ff: Under conditions of normal atmospheric pressure these relations are given, curves shown in Figures 4 and 5.32 Further codification of these relatYpn||j "From unpublished data of the author. " J. W. Bean, Physiol. Revs., 25, 1 (1945). "A. V. Bock, H. Field, Jr., and G. S. Adair, /. Biol. Chem., 59, 353 (1924). ` "A. V. Bock, D. B. Dill, L. M. Hurxthal, J. S. Lawrence, T. C. Coolidge, M. and L. J. Henderson, J. Biol. Chem., 73, 749 (1927). 'iff ssrV-'-YSS1' EFFECTS OF ABNORMAL ATMOSPHERIC PRESSURE 593 Pwwf^^thennultiple factors known to affect this system has been developed by K^gSif^n^and his associates,33 but for the present purpose these need not be jiafu'ssed.'here in detail. It is sufficient to point out that, since dependence on 'lloafrTalprSure of the gases has been established, the relationship holds regard Igfeexternal cause of the change in partial pressure. in the case of oxygen it is possible to interpret the partial pressure ^dissociation curve for hemoglobin in terms of altitude. In this case a '^^fecr^libr converting the atmospheric partial pressure to that actually found J Iraflblar surface must be made. Figure 6 shows theoretical and equilibrium BAROMETRIC PRESSURE, mm. H 700 600 500 400 300 200 100 80 60 Os 40 -CO- A.R.O. Ml I 1 ' 1 I ' ' ' I.................. . ' I 5 10 15 20 25 30 ALTITUDE InTHOUSANDS OF FEET . ,6. Effect of decreasing pressure on alveolar oxygen and carbon dioxide partial jg|u|ves AlC, At, and Aa: average of experimental data, subjects acclimatized to 1000 defers). Curves Bie, Bi, and Bi: average of experimental*.data, subjects acclimatized V*, r<M 1900 meters). Curves Ai and Bi: theoretical fall in oxygen partial pressure with no itilation. A.R.Q. = alveolar respiratory quotient. ftoiyliotfa carbon dioxide and oxygen pressures at the ,lung-blood interface * -l'"jlrcm platitudes. The deviations of the, experimental-.data are due mainly y&WSmi-qpg 0f "the body and not to the simple chemical relationships of the heir absorbent substrates.34 2. "Inert" Gases ^twi-.pqngSt^to-the-properties-of-chemicallj^-active-gases-as-discussed-abover ^gbehuyior' of the so-called inert gases of the atmosphere, such as nitrogen, Henderson, A. V. Bock, H. Field, Jr., and J. L. Stoddard, J. Biol. Chem., 59, 379 WJlhiE'rJ. HHeenderson, Blood. Yale Univ. Press, New Haven, 1928. 'Boothby, Ptoc. Staff Meetings Mayo Clinic, 20, 209 (1945). Mwgrf.,