50 
CHEMISTRY: HARKINS AND EWING Proc. N. A. S. 
and remained of that order for about six hours. The tube was sealed 
off while still at 600°, and was then opened under the hot liquid which 
had just been boiled to drive off dissolved gases. In some cases the char- 
coal was treated with the vapor of the liquid while it was still in the vacuum 
apparatus, and was then subjected to a second outgassing. It was found 
that it was not sufficient to reduce the pressure to 0.0001 mm. but that 
this low pressure had to be maintained for hours, if concordant results 
were to be obtained. Those who are familiar with vacuum work will 
realize that when a bulb almost completely filled with active charcoal is 
kept at 0.0001 mm. for hours at 600° C, a very low pressure when the 
temperature is considered, and is sealed off at this temperature and pres- 
sure, the pressure on cooling will fall to an exceedingly low value. It is 
probable that this pressure is much lower than can be obtained with the 
extremely efficient condensation pumps, that is, the pressure is probably 
lower than has ever been measured. 
A few of the results obtained by us for a high-grade, steam-activated 
charcoal (E 602), a 47.2 minute charcoal as determined by the accelerated 
chlorpicrin test, or about 700 minutes by the ordinary test, are given in 
table 1. The densities given here are those which the carbon would have 
if it filled all the space not occupied by the liquid, and if the liquids were 
incompressible. The densities given are the averages of very closely 
agreeing values. 
TABLE I 
Density and Pore-Volume Determinations for a Steam-Activated Cocoanut 
vShell Gas-Mask Charcoal CData at 20° C.) 
1 
LIQUID 
2 
DENSITY 
3 
PORE 
VOLUME 
IN 1 CU. CM. 
4 
PER CENT 
compressed 
12000 atmos- 
pheres! 
5 
SURFACE 
TENSION 
DYNES 
PER CM. 
6 
VISCOSITY 
IN ABSOLUTE 
UNITS 
0.865 
57.0 
Water 
1.843 
0.534 
20 . 51 
72.8 
0.0101 
Propyl alcohol 
1.960 
0.559 
22.93 
23.7 
0 . 0223 
Chloroform 
1.992 
0.566 
27.13 
0.0057 
2.008 
0.568 
28.88 
0.0064 
2.018 
0.571 
28.33 
0.0064 
2.042 
0.579 
2.057 
0 580 
25 . 37 
31.38 
0.0037 
2.112 
0.590 
27.0 
23.50 
0.0033 
Kther 
2.120 
0.592 
30.0 
17.1 
0.0024 
Pentane 
2.129 
0.593 
More 
About 15 
0.0024 
than ether 
1 Note. — The solubility of gases in these liquids increases in general with the per- 
cent of compression or the compressibility, but the order is not exactly the same. The 
values for the density and for the pore volume listed in this table are calculated on the 
basis of the incorrect assumption that the liquids are incompressible. The same values 
would be obtained if tlie liquids are compressible but are not compressed. 
