217 



aldehyde A consists of two aldehydes, and that the bisulphite 

 addition compound of the one with the high rotation is more 

 soluble in alcohol-ether than the other. Another sample of 

 aldehyde A having a rotation of —34°, after recombining 

 with sodium bisulphite, filtering, washing, and decomposing 

 with sodium carbonate, had a rotation of — 5*9°. The oxime 

 was also prepared from this latter sample, and it easily 

 crystallized when poured into water. It melted constantly 

 at 55*7° C. It was noticed that the less the rotation, the 

 easier the preparation of the oxime became. 



Conclusion. — The melting point of the oxime of cumic 

 aldehyde is 58° C, and as the constants of the aldehyde with 

 the small rotation are very like those of cumic aldehyde, and 

 the melting points of the oximes are approximately the same, 

 it appears certain that cumic aldehyde is a constituent of this 

 oil. The other portion of this aldehyde A is probably the 

 aldehyde which H. G. Smith previously named aromadendral. 

 (This term has recently been extended to cover the whole 

 of the aldehydes occurring in Eucalyptus oils.) 



Aldehydes B and C. 



The additive bisulphite compounds of these aldehydes 

 were not decomposed by sodium carbonate, but were by caustic 

 soda. Aldehyde C consists of two aldehydes, and it seems 

 probable that aldehyde B above is a mixture (probably in 

 different proportions) of the same two aldehydes which con- 

 stitute aldehyde C. It is probable that the addition com- 

 pound of these two aldehydes is very soluble, and hence while 

 the bulk of it is soluble in the sodium bisulphite solu- 

 tion, a small amount is precipitated along with the cumic 

 aldehyde and the aromadendral. The aldehyde B separat-ed 

 by Experiment g from the residual oil was distilled under a 

 pressure of 30 mm. The temperature rose slowly during the 

 distillation from 132° to 141° C. The distillate gave the fol- 

 lowing constants: — Specific gravity at ^-2-° C. =0*9469 ; cor- 

 rected to 15° C. =0'9502 ; rotation, — 997°; refractive index 

 at 20^ C. = 1-4899; dispersion, 0-01341. 



Aldehyde C separated from the crude oil by Experi- 

 ment c had a refractive index of 1"505. The aldehydes con- 

 stituting aldehyde C were separated from each other by 

 means of neutral sodium sulphite solution. 



Method. — Tlie aldehyde was shaken with a solution of 

 crystallized sodium sulphite (35 per cent., neutralized to 

 phenolphthalein), the liberated sodium hydroxide being con- 

 tinuously neutralized with normal sulphuric acid. The un- 

 ccmbined aldehyde was extracted by benzene. The 



G 



