Kreider — Oxygen in Air and in Aqueous Solution. 367 



described, and by means of a long nozzle could be conducted 

 to the bottom of eh and thus be admitted with but momentary 

 and slight contact with the air. The tube eh contained approx- 

 imately three cubic centimeters. With all the stop-cocks 

 closed, the flask was inverted several times and thoroughly 

 shaken, at the same time washing out the ends of the stop-cocks 

 with distilled water. After again placing the apparatus in its 

 position, enough potassium bicarbonate solution was admitted 

 through e to expel all the nitric oxide through d ; the bulb, a, 

 bolding sufficient of the bicarbonate to neutralize all the acid 

 taken. The bicarbonate being heavier quickly diffuses through 

 the contents of the flask and neutralizes the acid ; d and e are 

 kept closed for a minute with }> open so as to allow sufficient 

 of the liquid to escape into a beaker containing some bicarbon- 

 ate to provide space for the carbon dioxide evolved. Then the 

 flask is washed out and its contents titrated with arsenic. 



The bleaching, by the aid of starch for the final reaction, 

 can be accurately read to a single drop. Usually the reading 

 was verified by adding a drop of ^ iodine solution, which pro- 

 duced the characteristic color. 



Table II gives the results of a series of determinations. 





Table 



II. 





1. of Water taken. 



Temperature. 

 -° C. 



ASaOs 



required. 



cm*. 



Yol. of Oxygen dissolved 



in 1000 cm^ of water 



at 760"™. 



314-63 



20 



3-42 



6-04 





<t 



3-46 



6-09 





a 



3-40 



6-00 





(( 



3-41 



6-02 





ct 



3-43 



6-05 





if. 



3-40 



6-00 





(.(. 



3-36 



5-93 





(( 



3-40 



6-00 





<( 



3-40 



6-00 





(( 



3-50 



6-18 





u 



3-38 



5-96 





u 



3-40 



6-00 



The mean of these determinations gives 6-022°°^^ of oxygen 

 as the amount dissolved in distilled water at 20° C. and 760™% 

 and while some of the determinations vary considerably from 

 this mean, as a whole they are fairly accordant. This method, 

 moreover, is applicable to carbonated water. 



