The ketone reacts comparatively slowly with semicarbazide; hence, in 

 order to obtain a satisfactory yield, it is necessary to allow the reaction- 

 mixture to stand for several days. The semicarbazone, like the similarly 

 constructed carvenone semicarbazone, occurs in two modifications 1 ). The 

 a-modification melts at 224 to 226°. Being very sparingly soluble in 

 alcohol, it can be satisfactorily separated from the easily soluble /^modifi- 

 cation by boiling in absolute alcohol. 



0,1456 g. subst: 0,3355 g. C0 2 , 0,1190 g. H 2 0. 

 Found Calc. for C11H19N3O 



C 62,85 °/o 63,1 5 °/o 



H 9,08°/o 9,09°/o. 



The /^-modification, which is less easily obtainable in the pure state, 

 melts at 171 to 172°. 



0,1289 g. subst: 0,2977 g. C0 2 , 0,1067 g. H 2 0. 

 Found Calc. for C11H19N3O 



C 62,99 °/o 63,1 5 °/o 



H 9,20 °/o 9,09 °/o. 



When the semicarbazones are heated with acids, the ketones are re- 

 generated. With semicarbazide, the ketone which is obtainable from the 

 readily soluble semicarbazone again yields a semicarbazone mixture from 

 which we only isolated the sparingly soluble ^-modification, melting bet- 

 ween 224 and 226°. From this it may be inferred that the same ketone 

 forms the two semicarbazones. From synthetically prepared z^-menthenone, 

 Wallach 2 ) has only isolated the semicarbazone melting between 224 to 

 226°, a body "remarkable for the difficulty with which it is soluble". 

 Owing to the kindness of Prof. Wallach we were ourselves enabled to 

 prepare the ketone from 1,3, 4-trihydroxyterpane, placed at our disposal by 

 him, and to compare it with that from the peppermint oil. The m. p. of 

 a mixture of the two sparingly soluble semicarbazones showed no de- 

 pression. The small quantity available precluded further comparison. 



With hydroxyiamine the ketone yielded a normal oxime and an 

 oxamino-oxime. The former is obtained by treatment with the calculated 

 quantity of hydroxyiamine, but as, in the course of this reaction, some 

 oxamino-oxime is also generated, it is necessary to free the oxime by 

 distillation with steam from the oxamino-oxime adhering to it. Recrystallis- 

 ed from alcohol it melts at 107 to 109°. 



0,1248 g. subst: 0,3279 g. C0 2 , 0,1132 g. H 2 0. 

 Found Calc. for C 10 H 16 NOH 



C 71,67°/o 71,85° o 



H 10,08°/o 10,1 7°/o. 



The ketone can be regenerated by heating with acids. 



x ) Wallach, Terpene und Campher, Leipzig 1909, p. 373. 

 2 ) loc. cit. 



