30 IVAN C. HALL 



A duplication of this experiment using phenolphthalein instead 

 of methylene blue showed that CO2 also is probably similarly 

 concerned; for with the marble seal in the solution the alkalinity 

 of that portion below the seal was protected for over twenty-one 

 hours as against a failure above the marble but below the oil 

 within 1 hour, while with the marble in the oil the solution was 

 only faintly alkaline at one hour and frankly acid at three and 

 one-half hours. 



It is impossible to attribute any change in reaction directly 

 to contact with the oil in view of an experiment with oil layered 

 on standard buffer solutions of known acidity (pH = 5, 6, 7, 8, 

 and 9) and colored with brom-cresol purple and cresol-red in 

 their respective ranges for comparison with identical solutions 

 with out oil; there was not the slightest evidence of changed 

 reaction either after shaking together cold, or during, or immedi- 

 ately after heating. 



An attempt to make a better showing for the oil by heating 

 the mixture of alkaline glucose methylene blue solution in the 

 autoclave for twenty minutes at 25 pounds pressure (267°C.) 

 gave no better results. Neither was separate heating of solution 

 and oil either in the boiling water bath or in the autoclave, 

 followed by immediate layering, as efficacious in preventing the 

 return of color as heating together in the water bath. 



Vigorous boiling of the solution under the oil by the cautious 

 use of a 110°C. saturated salt solution while accelerating the rate 

 of decolorization failed to show any material advantage in 

 excluding the air as judged by the time in which the color returned. 



Several attempts to layer oil at or near its own boiling point 

 (about 300°C.) upon decolorized solution at 100°C. resulted 

 disastrously in breakage of glassware and almost explosive 

 scattering of hot oil. Cooled rapidly to about 120°C. in a few 

 exeriments I had the gratification of seeing the solution under 

 the oil, even without the marble seal, remain completely decolor- 

 ized for nearly twenty-four hours; with the marble seal in the 

 oil it remained so for much longer. In still other experiments 

 where the oil was heated to boiling and allowed to cool even for 

 a few minutes, to as low as 60°C. and then immediately brought 



