124 — 
temperatures (a-ionone). The most important physical constants of 
the two ionones are given below: 
Boiling point at 12 mm: 
^15°- 
n 
melting point of the 
thiosemicarbazone 
a-ionone 
,0 
127,6^ 
0,9338 
1,50001 (17,2'') 
12 1 
^-ionone 
134,6° 
0,9488 
1,52008 (17,5°) 
158° 
The conversion of terpene ketones into cyclic bases has again 
been studied in detail by Wallach^), as is proved by two treatises 
both representing a rich contribution of great value for chemical system- 
atics. Cyclic oxymethylene ketones react readily with semicarbazide 
solution (I); the semicarbazones thus obtained split off water, either 
voluntarily, or after addition of small quantities of mineral acids (cyclic 
semicarbazones) (II), these are decomposed by boiling with dilute 
sulphuric acid into carbonic acid, ammonia, and the corresponding 
pyrazol base (III). Taking menthone as an example, the conversions 
would take place in the following manner 
(I) 
H^C 
CH.C3 
CO 
C H • C3 
+ H2N.NH.CO.NHJ 
C==CH.OH 
H,C 
C^N.NH.CO.NH., 
C = CH.OH 
CH — CH„ 
CH.CH. 
H^C 
H,C 
(11) 
CH.C3H, 
C:N 
C:CH 
CH-CH. 
N.CO.NHg + H^O 
CH.C3H. 
H^C 
C = N 
C = CH 
CH.CH., 
NH + CO^+NHg 
Acyclic oxymethylene ketones react in an analogous manner 
excepting that oxymethylene acetone condenses with two molecules 
semicarbazide. 
The same scientist 2) reports further on a new cyclic base from 
methyl heptenone. Methyl heptenylamine absorbs not only one, but 
^) Liebig's Annalen 329 (1903), 109. 
2) Nachr. k. Ges. Wiss. Gottingen 1903, part 4 (according to Chem. Centralbl. 
1903, 11. 1324). 
