Origin. From time to time the seeds of Siam cardamoms, from Amomum Cardamomum, L. make their appearance in the London market, where they are known as camphor seeds because of their camphor-like odor. Upon distillation Schimmel & Co.1) obtained 2,4 p.c. of oil.
1) Liebig's Annalen 350 (1906), 168. - Nachr. K. Ges. Wiss. Gottingen 1907, Session of July 20.
Properties. At ordinary temperature this oil constitutes a semi-solid mass with an odor of camphor and borneol. In order to dissolve the separated crystals, the oil had to be heated to 42°; at which temperature the specific gravity was 0,905 and the angle of rotation + 38o 4'. S. V. 18,8; S. V. after acetylation 77,2, corresponding to 22,5 p.c. of borneol in the original oil; soluble in 1,2 vol. of 80 p.c. alcohol.
Composition. In order to separate the stearoptene, the oil was cooled down in ice and treated by centrifugal machine. From 800 g. of oil 100 g. of crystals were thus obtained. Dissolved in hot light petroleum and after the solution had been allowed to cool, there resulted 40 g. of nearly pure borneol which, after having been purified through its benzoyl ester, melted at 204°. In a 10 p.c. alcoholic solution it showed a specific angle of rotation [a]D20o + 42° 55'.
The light petroleum mother liquor left upon evaporation, a crummy mass which, after recrystallization from 80 p.c. alcohol, melted at 176 to 178° and had the properties of camphor. Its oxime melted at 118°. Its optical rotation was determined in alcoholic solution, [a]D + 45° 17' at 20°.
Hence the crystalline mass which separates from Siam cardamom oil'2) consists of a mixture of d-borneol and d-camphor, the two compounds being present in approximately equal parts.