Where the dissolved gas consists of more than one kind, a compromise value of t 

 should be used in performing the extrapolation indicated by Equation [la]. Thus for air, a 

 suitable value is nine-tenths of the response time t^. 



EXPERIMENT 



APPARATUS AND PROCEDURE 



The earliest experimental tests of the principle outlined in the Introduction were per- 

 formed with laboratory equipment arranged in the fashion shown in Figure 1. These experi- 

 ments indicated the feasibility of the method and led to the version of the instrument shown 

 in Figures 2 and 3. The glass dome enclosing the nozzle and gas space is an inverted 

 Pyrex test tube. The mouth of the tube is sealed with litharge-and-glycerine compound into 

 a flanged receptacle. The latter is fastened with cap screws to the lower part of the cham- 

 ber, and the joint is sealed by means of an "0"-ring. Except for the glass dome, all the 

 parts of the chamber are made of brass. The purpose of the bulbous lower portion of the 

 chamber is to reduce the velocity of the outgoing liquid so that gas will not be carried out 

 in the form of entrained bubbles. It is shown in the Appendix that the presence of undissolv- 

 ed gas in the outflow introduces an error in the indication of the instrument. A glass sight 

 tube sealed into the dome at the top and at the side is intended as an aid in determining the 

 level of the liquid in the chamber under conditions of operation, where the main surface is 

 disturbed by the falling liquid. 



Level Control 

 Electrodes- 



-To Reservoir 



Figure 2 - Schematic Diagram Showing 

 Installation of Air Content Meter 



The automatic control was not installed at the time 

 of the experiments described in the text. 



Figure 3 - Meter Chamber, Pressure Gage, 

 and Flowmeter Installed 



