116 Dr. H. T. Brown and Mr. F. Escombe. [Jan. 9, 
water, the temperature of which was observed at frequent intervals.* Six 
experiments of this nature were made between 13°°7 and 23°°7 C., ordinary 
air being used, of which the content of carbon dioxide was independently 
observed with the Reiset’s apparatus. 
? 
Table IJ.—Showing the Influence of Temperature on the Coefficient of 
Absorption of CO, by the Surface of a 4 per cent. NaOH Solution. 
Coefficient of absorption of 
CO: per square centimetre 
of liquid surface per hour, 
for 1 vol. of CO, in 10,000 
Temperature. vols. of air (dry). 
Seer 00519 
15°3 0:0537 
La 0:0537 
oss 00583 
ZS 00623 
23° 7 0:0635 
On plotting out these results, it may be seen that within the experimental 
limits the coefficient of absorption varies directly with the temperature, and 
that an increase of temperature of 1° C. corresponds to an increase of 0:0018 
in the absorption coefficient. Hence the value of this coefficient for any 
temperature ¢° within the above limits will be represented by 0:0356+ 
t° 00018, 0:°0356 being the coefficient of absorption at 0° C., as determined by 
extra polation. 
Assuming now that the relation of the partial pressures to absorptions is 
of the simple nature already postulated, then the volume of carbon dioxide 
contained in 10,000 volumes of dry air should be given by the formula 
A 
00356 + 2° x 0:00118 ’ 
where A represents the carbon dioxide absorbed per square centimetre of 
surface per hour, at temperature ¢°, from an air-stream which is drawn over 
the absorbing liquid at a sufficient rate to ensure the limit of maximal 
absorption being reached; A being stated in terms of cubic centimetres at 
normal temperature and pressure. 
With the knowledge thus gained we are now in a position to compare the 
estimations of carbon dioxide made by means of the method of surface- 
absorption with those made with the Reiset’s apparatus. 

* Tn order to avoid evaporation and consequent cooling of the absorbing solution, the stream of 
air was previously saturated with moisture before being passed into the absorption apparatus. 
