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PHYSICS: H. B. LEMON 
of from 100 cm. to 0.00001 cm. A small Geissler tube was in communication 
with the charcoal bulb for a rapid means of observing the character of the gas 
content and, quahtatively, the pressure. After outgassing through cock, 1, 
this was closed and cock, 2, opened. The charcoal was thus exposed to a 
constant volume of 873 cc. initially filled with air at about 90 cm. pressure. 
This initial pressure was varied slightly as the room temperature varied so 
that the enclosed mass of air was constant, i.e. 1.2 grams. The air was im- 
mediately adsorbed and the rate of fall of the pressure observed as long as 
it was appreciable. 
Results are expressed graphically by plotting the logarithm of the pressure 
in cm. against the logarithm of the time in minutes elapsing after the cock, 
2, was opened. Figure 1 shows curves for three different samples under 
identical conditions. A was carbonized at 900°C., B at 850°C. and C at 800°C. 
They were all outgassed simultaneously for 6 hours at 425 °C. and tested in 
rapid succession on the same apparatus. The enormous difference in rate is 
obvious in view of the logarithmic scales. The initial pressure of 90 cm. is 
reduced in 10 minutes to 20 cm., 0.71 cm. and 0.0003 cm. for 'A, B and C 
respectively. 
Figure 2 shows the results of successive 'runs' on the same specimen. 
This specimen was carbonized at 850°C. and the outgassings were all identical 
at 600° for 4J hrs. It shows a systematic increase in rate after each run and 
subsequent outgassing becoming equal after 10 consecutive runs to the former 
sample shown as C in figure 1. 
Figure 3 shows an effect which was controlled so as to be the converse of 
that illustrated in figure 2. It depicts also successive runs on a single speci- 
