TABLE 1 

 Solubility Coefficients for Oxygen and Nitrogen in Water 



Temperature 

 degC 



Oxygen 



Nitrogen 







0.0489 



0.0235 



10 



0.0394 



0.0193 



20 



0.0333 



0.0166 



30 



0.0289 



0.0149 



40 



0.0264 



0.0136 



A second principle relevant to the operation of the instrument is known as Dalton's 

 Law.^ Dalton's Law states that in a mixture of two or more gases, each gas behaves inde- 

 pendently of the other gases present, the equilibrium concentration of each gas in solution 

 being determined by the partial pressure exerted only by that gas on the exposed surface of 

 the liquid and by its own solubility in that liquid. A consequence of this behavior is that the 

 relative proportions of the dissolved gases may be different from the corresponding relative 

 proportions in the gas mixture with which the solution is in equilibrium. A pertinent example 

 is the case of a solution consisting of oxygen and nitrogen in water, in equilibrium with the 

 ordinary atmosphere. The solubility coefficient of nitrogen is only about one-half that of oxy- 

 gen. Consequently, the dissolved gas, when extracted, proves to be a mixture of the two 

 gases in the proportion of two volumes of nitrogen to one volume of oxygen though the atmos- 

 phere is a mixture having the proportions of four volumes of nitrogen to one volume of oxygen. 



The instrument described in this report makes use of the principles outlined above and 

 in the following section to establish an equilibrium condition between the gas pressure in a 

 fixed volume in a closed chamber and a continuously flowing sample of liquid passing through 

 the chamber. In the construction whose evaluation is discussed, water is sprayed into the 

 chamber through one or more "atomizing" nozzles. The necessary surface exposure and 

 mixing take place not only in the spray itself but also in a film of liquid on the inside walls 

 of the closed chamber, especially in the upper part of the film which is supported and agitated 

 by the impinging spray. This arraiigement was selected for tests on the basis of apparent 

 simplicity rather than for maximum effectiveness in mixing. Various other t^pes of scrubbing 

 and absorption devices are known and used in industry.® It is recognized that either analy- 

 sis or experiment may prove some of these more effective than that chosen. Results obtained 

 indicate that the method used is a valid and practical one and that it provides a continuous 

 reading with acceptable accuracy. Further development may be aimed at increasing the rapi- 

 dity of response which, at present, does not allow significant indications of changes in air 

 content of the inflowing sample within a period of less than about 10 minutes. 



