— 192 — 



Furthermore, citron ellal was converted by Tiemann's and Schmidt's 

 method into z-ro-pulegol and the latter into w-pulegone; in this 

 case also the oxime was identical wiih that obtained from pulegone. 

 In the course of the last-named manipulation two oximes were formed, 

 both of which, contrary to the results obtained by Tiemann and 

 Schmidt, volatilised with steam, and could only be separated with 

 difficulty into an inactive oxime (m. p. 138 to 13 9 ) and into the 

 active oxime referred to above (m. p. 122 ) by recrystallisation from 

 methyl alcohol. In certain circumstances, as shown ay Harries, it is 

 even possible that in the course of the conversion of citron ellal only 

 an inactive ketone is formed. 



Camphor. The preparation of isomeric borneol carboxylic acids 

 by means of the electro-reduction of camphocarbonic acid was the 

 subject, several years ago, of a short paper by Bredt and Burkheiser L ). 

 A detailed communication on this reaction and the conversions which 

 are related to it in further sequence has now been published by Bredt 2 ) 

 in conjunction with Scheen, Quaritsch, Wornast and Langguth. The 

 apparatus employed for the electrolytic process has been improved in 

 this respect that the spaces for the anodes and cathodes have been 

 separated by a specially arranged diaphragm which makes it possible 

 to keep the cathode-liquid in constant agitation by means of a stir- 

 ring-rod. A lifting tackle of peculiar and ingenious construction, with 

 lever-movement, and kept at a fixed height by means of a float, 

 keeps the anode-liquid (concentrated potash-solution) at a stable 

 level, while the liquid is protected from heating and evaporation by 

 means of an internal condenser. The termination of the reduction (for 

 which about nine times the theoretical amperes was needed) was indi- 

 cated by the sharp reaction of camphocarbonic acid with ferric chloride. 

 Even traces of the acid may be detected in the colorimeter by the 

 bluish-green colour. The crude borneol carboxylic acid, of which 

 88 °/ of the theoretical yield was recovered, was split up in the two 

 isomerides (m. p. 171 and 10 1°) already referred to by dissolving 

 the crude acid, which was entirely free from ether, in 1 to iV 2 times 

 its volume of toluene with the application of heat, and by leaving the 

 solution to stand for 24 hours at the ordinary temperature of the 

 laboratory. In the course of this process the greater part of the acid 

 with m. p. 171 separates out first. By shaking the separated mother- 

 liquor in a freezing -mixture the isomeric borneol carboxylic acid 

 (m. p. 101 ) is next separated. Further quantities of both acids may 

 be obtained by leaving the solution to stand alternately at ordinary 

 temperature and by subsequent cooling, if need be after concentrating 



*) Liebig's Annalen 3i8 (1906), 199; Report October 1906, 135. 

 2 ) Liebig's Annalen 366 (1909), 1. 



