328 GASOMETRIC-VOLUiMETKIC METHODS 



2. Introduce the gas sample (about 10 jul.) into the absorption 

 chamber following the steps shown in Figure 102. Guide the tip of 

 the pipette so that it does not touch the wall of the chamber during 

 the transfer. 



3. Draw the mercury back into the capillary until the meniscus 

 is at the mark, and then take the first micrometer reading. 



4. Draw the gas into the capillary, and after it a little mercury. 



5. Suck away the mercury left in the absorption chamber and 

 replace it with manometer fluid. 



6. Expel the residual mercury in the capillary into the manom- 

 eter fluid contained in the absorption chamber. Draw in a little of 

 the fluid, and suck away that remaining in the chamber. Leave only 

 2 mm. of the fluid in the capillary. 



7. Bring the gas-fluid meniscus to the mark and take a second 

 reading. The volume of the sample is obtained from the difference 

 between the two readings. 



8. Move the manometer fluid out into the absorption chamber 

 again and fill the chamber with the potassium hydroxide solution td 

 join the fluid without enclosing any air bubbles. 



9. Move the gas sample out into the alkali in the chamber until 

 the gas bubble breaks loose. Then move the bubble back and forth 

 by tipping the instrument. 



10. Draw the bubble back into the capillary and take a third 

 reading when the gas-mercury meniscus reaches the mark. 



11. When the last of the gas has been drawn into the entrance 

 of the capillary, replace the alkali by manometer fluid and then 

 suck all of the fluid away except a short drop in the capillary. 



12. Move the fluid-gas meniscus to the mark and take a fourth 

 reading. The volume of the sample minus the carbon dioxide is 

 obtained from the difference between the third and fourth readings. 



13. Repeat steps 8-12 using the hydrosulflte solution to absorb 

 the oxygen. Allow 2 min. for the oxygen to be absorbed. The gas 

 remaining after this absorption is entirely nitrogen. 



(6) Berg Simplified Gas Analyzer 



Using the principle of the Scholander micrometer-burette gas 

 analyzer. Berg (1946) employed the simplified apparatus illustrated 

 in Figure 103. The thermometer tubing is 6 in. long and has a bore 

 of 0.11 mm. The water jacket surrounding it affords protection 



