[ 540 ] 

 LXXI. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 396.] 

 November 21, 1867. — Lieut. -General Sabine, President, in the Chair. 



THE following communication was read : — 

 " Contributions to the History of Methylic Aldehyde. ,, By 

 A. W. Hofmann, LL.D., F.R.S. 



" The aldehyde of the methyl-series is not known ; " all the 

 chemical manuals say so, and for the last twenty years my students 

 have been duly informed thereof. It will scarcely appear strange 

 that more efforts to become acquainted with that body should not 

 have been made, since the masterly picture which Liebig has deli- 

 neated of the aldehyde par excellence embraced as it were the history 

 of the whole class, and of course also of the aldehyde in question. 

 Nevertheless methylic aldehyde deserves our consideration for more 

 than one reason. As one of the simplest terms of the monocarbon- 

 series, occupying a position intermediate between marsh-gas and 

 carbonic acid, as a link of transition connecting methylic alcohol 

 and formic acid, as either aldehyde or acetone, according to the 

 point of view from which we look upon it, the compound CH 2 O 

 illustrates a greater variety of relations than any one of the higher 

 aldehydes. But in addition to the interest with which the methyl- 

 compound has thus always been invested, this substance possesses 

 special claims upon our attention at the present moment. Our actual 

 method of treating organic chemistry for the purposes of instruction 

 almost involves the necessity of starting from the methyl-series. 

 The simplest of aldehydes thus acquires quite an especial importance ; 

 and all those who, like the author of this note, are engaged in teach- 

 ing, cannot fail to have sadly missed a compound which is the carrier 

 of such varied and interesting considerations. 



The desire which I have frequently felt in my lectures of develo- 

 ping the idea of the genus aldehyde, when speaking of the methyl- 

 compounds, has more than once induced me to attempt the prepa- 

 ration of methyl-aldehyde, but it was only at the conclusion of my 

 last summer course that I succeeded, to a certain extent at all events, 

 in attaining the object of my wishes. 



A substance possessing the composition and the properties of me- 

 thylic aldehyde is formed with surprising facility if a current of at- 

 mospheric air, charged with the vapour of methylic alcohol, be 

 directed upon an incandescent platinum spiral. 



The bottom of a strong three-necked bottle, of two litres capa- 

 city, is covered to the height of about five centimetres with mode- 

 rately warm methylic alcohol. The first neck is provided with a 

 tube descending to the very surface of the liquid ; into the second 

 is fixed a loosely- fitting cork, which carries the platinum spiral ; the 

 third one, lastly, communicates with the upper end of a condenser, the 

 lower end of which is fastened into a two-necked receiver. This receiver 



