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this process of transition which vol must he of a chemical nature. 



But a great difficulty to the theory arises from the fact that ad- 

 sorption of odour on metal surfaces appears to be a general pheno- 

 menon. This appears from similar systematic experiments as with 

 muse for two other characteristic smelling substances. 1 chuse ionon, 

 a substance dissolving in water as well as in liquid air and seatol, 

 a substance for which this has not yet been investigated. 



Ionon, when diluted 1 to a million in an aqueous solution of 

 0,5 ° „ antilehrin, and evaporating into a passing air-current which 

 in the well-known manner passes through cylinders of different 

 material, leaves an adsorption which disappears almost immediately 

 witli porous porcelain, arc-lamp carbon, glass, silver, sticks to tin 

 for a very short time, to lead, containing tin, scarcely for a day 

 to nickel and copper for about two days, to aluminium for 2 7 3 days 

 and to iron and steel for about four days. 



Seatol, when dissolved in proportion of J to 1000 in liquid paraffin 

 and evaporating into passing air and passing' in the well-known 

 manner through cylinders of different material, leaves an adsorption 

 which disappears almost at once with porous porcelain and arc-lamp 

 carbon, in a few hours with glass, slicks to lead, containing tin, to 

 lead, silver and tin for about a day, to copper 3 days, to iron 4 to 

 5 days, to steel 10 to 13 days, to aluminium oxer 10 days. 



Hence ionon adheres most to the substance which does not take 

 up muscon at all, i.e. to steel; seatol most to aluminium which 

 shows a comparatively very small adsorptive power for muscon 

 (aluminium does not keep muscon for 24 hours). 



In order to explain these deviations one is forced either to assume 

 a peculiar modification of the solubility, caused by the dissolution 

 of the specific metallic particles in the condensation layer, or to 

 assume an absorption in the metal itself. To me it would seem that 

 the collected facts do not at present admit of a choice between these 

 two possibilities, although the small influence of the muscon density 

 in the air would point to an adsorption compound with the metal. 



