73 X.-Note on the Absorption of Mixed Vapoum by Charcoal. By JOHN HUNTER,M.A. F.C.S. Chemical Assistant Queen’s College Belfast. (Read January 20 1870.) THEresults obtained by absorbing a mixture of two vapours by means of cocoa-nut charcoal were published in the I‘ Journal of the Chemical Society,” May l8G8. It was found that the absorption was greatly increased when one of the vapours was at a temperature near to its point of condensation. Thus in the case of ethylic alcohol and water the amount of mixed vapour absorbed changed rapidly according as the proportion of the former to the latter varied from 1 1 to 1 3 one volume of cocoa-nut charcoal absorbing 187.2 volumes in the first case and 255.4 volumes in the last case at the temperature of 1OOOC.When the experiments were repeated at a tem-perature considerably above the Boiling point of water (about 160’ C.) the absorption diminished with the increased pro-portion of water from 58.1 to 37.6 an effect naturally to be expected when we reflect that alcohol vapour is much more largely absorbed than that of water at this temperature. It appeared to me that these experiments might be explained as follows :-When a fragment of charcoal is introduced into a mixture of two vapours the one which is nearest to its point of condensation is absorbed and this vapour in its condensed con- dition in the pores of the charcoal absorbs the other vapour pre- viously uncondensed. According to this view we have a succes-sion of condensations going on the total absorption depending not merely upon the power which the charcoal has of absorbing the vapours but oii a complex effect combining the absorption of the first vapour by the charcoal and then the absorption of the second by the product of the absorption of the first.If this theory is correct we should have the vapour of water mixed with gaseous ammonia (obtained by heating the solution of the gas in water) much more largely absorbed than either the gas or the water separately. On making a set of experiments with a solution of ammonia of sp. gr. 0.88 I found the absorp- tion enormously increased the average absorption by one VOL. XXIII. G ANDREWS ON THE CONTINUITY OF THE GASEOUS volume of cocoa-nut charcoal at looo C. and 706-2 mm. being 313.6 volumes. I conclude then that the water-vapour is first condensed in the charcoal and as this fluid has the power of absorloing ammoniacal gas to a much greater extent than char- coal we have the gas Condensed in the water contained in the pores and a greatly increased absorption occurs. The following are the various experiments :-Val. absorbed by one vol. Temp. C". Pres. in mm. of Cocoa-nut Charcoal. 316 *6 100" 714 -5 311 -1 7) 711 *6 816 *2 17 694 *6 309 -4 693 -1 >7 315-0 1) 717 -2 Mean.. . 313 *6 100 -0 706 *2