380 GASOMETRIC-MANOMETRIC METHODS 



Holter (1943, page 466) has chosen the following cases from Linder- 

 str0m-Lang (1943) for which formulas for AV are given which are 

 simplified and adequate for practical purposes : 



Case 1. The solubility of all gases present is low. This case comprises all ex- 

 periments in air, Na or O2 wherein CO2 does not occur or in which all the CL 

 formed disappears completely (respiration experiments in solutions without 

 carbonate buffers, in which the CO2 produced is absorbed by alkali). (Linder- 

 str0m-Lang 1943, page 369). 



In this case we find for all experimental procedures which may come into 

 consideration in practice: 



AV = VAP/Po 



Case 2. The gas to be measured is soluble in the liquids of the diver charge 

 (CO2). The amount of this gas is small (^5% of the total gas) in proportion 

 to the other gases. The latter are sparingly soluble and do not change in quan- 

 tity. This case includes inter alia all experiments which are based on the cir- 

 cumstance that acid is formed or disappears in a system containing carbonate 

 buffer (Linderstr0m-Lang 1943, page 371). 



In this case we find — under the assumption that the equilibrium pressure and 

 the "basic pressure" differ no more than 50 cm. from each other, that the vol- 

 ume of the oil seal is small {Yoii < 0.5m1), and that narrow-necked divers with 

 glass stoppers in the mouth seal are used: 



' ^ V ) 



where Vw = the volume of the bottom drop, a'coi = the absorption coefficient 

 (not referred to 0", but to i°) of CO2 in the bottom drop at 760 mm. Hg and t" 

 (for water at 22.5°, has the value 0.89; for definition of q!'co2 (and /S'coj) see 

 Linderstr0m-Lang (1943, page 366). 



The insertion of A F and AP for the original differentials dV and dP in- 

 stead of an integration is permissible also in this case, as shown by Linder- 

 str0m-Lang (1943, page 371), {i.e., the error involved is below 1%), provided 

 the pressure change A P does not exceed 50 cm., Brodie solution — which it 

 never does in practice. 



Case 3. Like case 2, except that also one of the sparingly soluble gases (O2) 

 varies in quantity. This case includes respiration measurements in which the 

 CO2 evolved is not absorbed (Linderstr0m-Lang, 1943, pages 372 and 390). 



In this case we find, under the same conditions as in case 2, augmented by 

 the condition v^ < 0.2 V, as well as under the assumption that the amount of 

 CO2 does not exceed 5% of the total gas: 



^y^^ _,_ AFco^ ^ VAP 



1 4- (Vwa'c02 + Voil /3C02)/F Pq 



Where Vot and FcOz = the volumes of O2 and CO2 in the diver, /3cOi the 

 absorption coefficient (as above) of CO2 in paraffin oil at 760 mm. Hg and t° 



