THE CHEMICAL NEWS AND JOURNAL OF PHYSICAL SCIENCE. WITH WHICH IS INCORPORATED THE "CHEMICAL GAZETTE." A Journal of Practical Chemistry IN ALL ITS APPLICATIONS TO PHARMACY, ARTS, AND MANUFACTURES. EDITED BY JAMES H. GARDINER, F.C.S. VOLUME CXXI. 1920 LONDON: PUBLISHED AT THE OFFICE, 97, SHOE LANE, E.C.4. AND SOLD BY ALL BOOKSELLERS.^ MDCCCCXX. WORK was only done at pressures below atmospheric. Six rubber stopper carrying a A good water pump was used as aspirator, and as the necessary pressure was reached the aspirator tube was closed, using a screw clip. The pressure was noted at intervals, temperature being kept constant by having the vessel immersed in jar of cold water surrounded by nonconducting material. Experiments were done with each charcoal at two or three different pressures. Occasional blank experiments were done as a control. The pressure in all cases at first increased and ultimately decreased, but this behaviour varied with the charcoal used. The first effect of aspiration would be to remove the gas on the charcoal surface. The increase in pressure would therefore be due to escape of gas from the interior, subsequent decrease being due to renewed surface condensation. In no case was the initial pressure regained, but the results give a good index as to the inner structure of the charcoals used. Thus, where rapid pressure increase is noted, a complex internal structure may be surmised Cocoanut, fruit stone, &c. In the case of birch dust its gas-adsorbing capacity depends mainly on surface effect. The palm nut charcoal used was in large pieces, so that most gas it retained would be by absorption. Time (mins.). Pressures in centimetres, Hg. 20 O 41 9 60'0 22.2 44 1 62.1 45.6 63.1 25 23.8 40 23.8 45.5 62.8 625 |