206 SCIENCE PROGRESS 



has taken on a new interest, such equilibria being now attri- 

 buted quite logically to adsorption effects, effects which in the 

 earlier days were not sufficiently recognised. 



References 



i. Duhem, Traitd dlementaire de Micanique chimique (1897). 



2. Pelabon, Comptes Rendus, 135, 35, 686 (1897). 



3. Bodenstein, Zeitsch. phys. Chem. 29, 155, 315 (1899). 



4. Duhem, loc. tit. 29, 711 (1899). 



5. Bodenstein, loc. tit. p. 429. 



6. Bancroft, Journ. Physical Chem. 22, 22 (1918). 



ORGANIC CHEMISTRY. By P. Haas, D.Sc, Ph.D., St. Mary's 

 Hospital Medical School, London. 



Under the title of " The Crotonisation of Acetaldehyde " 

 Sabatier and Gaudion {Comptes Rendus, 191 8, 166, 632) describe 

 a peculiar series of reactions which result when ethyl alcohol 

 vapour is slowly passed over uranium oxide at 360 C. ; de- 

 hydrogenation and dehydration take place in one process, 

 the alcohol being converted into crotonic aldehyde. Instead 

 of starting from ethyl alcohol a better yield of crotonic aldehyde 

 may be obtained by employing vapour obtained by heating 

 paracetaldehyde. If the resulting product is roughly frac- 

 tionated and the fractions 90-1 30 and 130-220 are separately 

 passed together with hydrogen over reduced nickel heated 

 to 1 70° normal butyl alcohol and normal hexanol are obtained. 

 The application of catalysts to the preparation of amines 

 is illustrated by a recent paper of Mailhe and de Godon 

 {Comptes Rendus, 191 8, 166, 467) in which these authors claim 

 that by passing a mixture of the vapours of aniline and methyl 

 alcohol in excess over aluminium oxide at 400-430 a mixture 

 of mono- and dimethyl anilines is obtained ; similarly toluidine 

 and methyl alcohol passed over aluminium oxide at 350-400° 

 give a mixture of mono- and dimethyl toluidines {loc. cit. p. 

 564). The same authors (/. Pharm. Chim. 1917 [vii], 16, 225) 

 also claim priority over Sabatier and Gaudier {Comptes Rendus, 

 1907, 165, 224) in the discovery that primary amines may be 

 converted into the corresponding nitrites by passing them 

 over heated finely divided copper or nickel. Whatever the 

 merits of the controversy may be, the reaction is an interest- 

 ing example of reversible catalysis, the opposite reaction — 

 namely, the hydrogenation of nitrites to amines by means of 



