Absorption of gases by charcoal in vacua

Abstract

Work of Dewar and Others. -- That charcoal is a good obsorbent of gases has long been know. The subject was first investigate by Saussure, and a detailed examination of this property of charcoal was made by Hunter (Phil. Mag. 4, vol. XXV, p. 364. 1863). Of all the charcoals he examined that made from cocoa-nut had by fat the greatest absorbing power, one volume of charcoal absorbing 171.7 volumes of ammonia, 17.9 of oxygen and 4.4 of hydrogen. It was not until 1874 that Sir James Dewar began his investigations of charcoal absorbing power. He found that when charcoal is first heated then exhausted to expel gases already absorbed, and finally cooled inliquid air, 450 cc. of gas is absorbed by each volume of charcoal. While cocoa-nut charcoal functions best, any kindwill do -- even that of blood.