[mclean] 



ADSORPTION OF GASES 



191 



Figure 3 



If log X be plotted against log p, the curve obtained is a straight 

 line (see Fig. 3), which shows that the equation giving the relation 

 between the amount and the pressure is of the form: 



X = ap^ 



where a and b are constants. Substituting the above results in this 

 equation, it becomes: 



x=-43p-9 



When the temperature of the lignite was much below the tempera- 

 ture of the room, a correction had to be made for the fall of pressure 

 in the apparatus due to the cooling of the lignite tube. The amount 

 of this correction was determined experimentally. The lignite was 

 removed and the tube filled with an equal volume of a non-absorbing 

 material (copper). The cooling agent was then applied and the fall 

 of pressure noted. A series of readings showed that the fall of pressure 

 is proportional to the initial pressure. This correction has been ap- 

 plied to all the pressure readings given for the other two temperatures. 



The following results were obtained with the lignite at — 78°C.: 



