P — 141 — 



of oxidising the aldehydes it was vigorously stirred for about 3 hours 

 with freshly precipitated silver oxide. When the odour of «,/?-hexylenic 

 aldehyde has disappeared the oxidation-process is at an end. By treating 

 the mixture with baryta solution the silver salts were converted into the 

 baryta salts. The whole mass was filtered and a certain portion of the 

 distillate was distilled off, after which the remainder passed over without 

 giving any odour. The acids corresponding to the aldehydes are then found 

 to be contained in the distillation residue in the form of baryta salts. 



Part of the baryta salts was used for the identification of the formic 

 acid 1 ). It was identified by the behaviour of its silver salt (turning black 

 when heated), by the reduction of the mercuric chloride, and, lastly by 

 its behaviour towards concentrated sulphuric acid (formation of carbonic 

 oxide). These tests proved the presence of formaldehyde in hornbeam 

 leaves. It is not possible to detect the aldehyde in the plants by the aid 

 of colour-reactions, but by the method described above it can be identi- 

 fied above suspicion. It occurs in the leaves in exceedingly small pro- 

 portions only. 



With the object of demonstrating the presence pf the other acids 

 corresponding to the aldehydes, Curtius and Franzen 2 ) distilled the baryta 

 salts with phosphoric acid. The distillate was extracted with ether and 

 the ethereal and aqueous portions were worked up separately. In the 

 portion soluble in water the formic acid was destroyed by heating with 

 an excess of yellow mercuric oxide on the water-bath. The authors at- 

 tempted to separate the remaining acids by fractional precipitation with 

 silver nitrate, but without success. Ultimately the separation was effected 

 by fractional distillation. The presence in the aqueous solution of acetic 

 and butyric acids was established; propionic acid was either absent or 

 occurred in traces only. 



The acids which were present in the ethereal solutions were also 

 separable by fractional distillation. The following were found present: 

 w-butyric acid, «-/?-hexylenic acid, and most probably valeric acid. It 

 follows that hornbeam leaves contain formaldehyde, acetaldehyde, n-butylic 

 aldehyde, «-/?-hexylenic aldehyde and several of the higher homologues of 

 hexylenic aldehyde. By far the principal of these, in respect of quantity, 

 is hexylenic aldehyde; acetaldehyde and w-butylic aldehyde also occur in 

 kponsiderable proportions, but the others are only slightly represented. 



For the purpose of identifying propionic acid the authors attempted to 

 convert it into its hydrazide, but when heating with anhydrous hydrazine 

 they obtained an already known body, namely diethyl-n-amido-triazol, 

 m. p. 166 to 167°. 



*) Curtius and Franzen , Sitzungslerichte der Heidelberger Akademie der Wissenscha/ten. 

 Section A, 7 th paper. This paper, as well as Nos. 8 and 9 have been kindly sent to us by 

 the authors. 



*; Ibidem, 8 th paper. 



