GAS ANALYSIS . 329 



against temperature change during the analysis. A saturated solution 

 of lithium chloride, preferably equilibrated with gas of approxi- 

 mately the same composition as the sample to be analyzed, is used 

 to fill the apparatus. The gas sample is introduced into the absorp- 

 tion chamber while the instrument is held vertically with the cham- 

 ber end down. By opening the screw clamp on the rubber tubing 

 attached to the capillary, the gas is drawn into the latter and the 

 volume is determined by noting the length of the gas column and 

 multiplying it by the cross-sectional area (0.0095 mm.-). The liquid 

 in the absorption chamber is then replaced by the gas-absorbing 

 solution (lithium chloride containing potassium hydroxide for car- 

 bon dioxide, and alkaline pyrogallol for oxygen) and the gas is 

 forced out into the absorption chamber. The unabsorbed portion of 

 the gas is then drawn back into the capillary and its volume is 



Absorption chamber Clamp Glass rod 



/ ^_^^ . , ...,, ,, ■"''■'■'"'"'^'1^ ^ I Fig. 103. Simplified 



f ^ ' . J .; j'n ^ ^^^ analyzer. 



^ ^ .. .. .-..^Z y ij ' /"' ' From Berg (1946) 



Thermometer tubing ^ Water lacket ^ Pressure tubing 



measured. To be sure of complete absorption the gas is re-expelled 

 into the absorption chamber and after a number of seconds redrawn 

 into the capillary. This process is repeated until no change in the 

 volume of the residual gas is observed. 



The small bore of the capillary enables the analysis of samples in 

 the range 0.4-1 fA. Under the most favorable conditions the experi- 

 mental error can be reduced to <0.3%. The chief source of error is 

 the diffusion of the gas into the lithium chloride solution and hence 

 the need for saturating this solution with gas of approximately the 

 same composition as that of the sample to be analyzed. There might 

 be an advantage in using mercury as the analyzer fluid in a manner 

 similar to that employed by Scholander with the micrometer-burette 

 apparatus. 



(c) Scholander-Ronghton Syringe Gas Analyzer 



The syringe gas analyzer, first described by Scholander and 

 Roughton (1942), has been used primarily for the estimation of 

 gases in blood samples of the order of one drop. Analysis can also 

 be performed on other fluids, and, in general, the apparatus may be 

 used for the analysis of components in gas mixtures. As applied to 



