LEPTOSPERMUM AND ITS ESSENTIAL OIL. 179 
boiling at 110—112° (12 m.m.) which was about 427 of the 
Se eication of Citronellal.—The fraction of lower 
boiling point was a colourless oil of a strong citronellal 
odour, its specific gravity at 12° OC. was 0°8577; optical 
rotation at 20°C., a> + 8°61°, equal to a specific rotation 
[alp 20° of + 10; refractive index mp 20°, 1°4482. 
Molecular weight.—The molecular weight of this alde- 
hyde, determined by the Landsberger boiling point method, 
using acetone as solvent, gave the following results:— 
ei 1612 ems. of aldehyde in 27°5 c.c. of acetone elevated the 
boiling point 0°6° C. indicating a molecular weight of 156°2. 
1°1612 grams in 36°5 c.c. acetone gave an elevation of 
0°45°C. Molecular weight 156°8. The molecular weight 
of citronellal = 154. 
Derivatives.—The naphthocinchoninic acid derivative 
was prepared in the usual way from pyruvic acid and P. 
naphthylamine and the crystalline product purified; it 
melted sharply at 225° C. 
Citronellyl £. naphthocinchoninic acid melts at 225° C. 
With semicarbazide hydrochloride it gave a crystalline 
semicarbazone which melted at 78 — 79° C. 
OCitronellyl semicarbazone melts at 82°5° ©. On reduc- 
tion it yields an alcohol of specific gravity +3° C. 0°8602, 
boiling at 226° C. (761 m.m.) and giving a silver salt of its 
phthalic acid ester melting at 123° ©. Records of the 
melting point of the silver salt of citronellyl phthalic acid 
vary from 120 to 125°C. It is thus evident that the 
aldehyde boiling at 93 —94° O, (12 m.m.) is citronellal. 
Identification of citral.—The aldehyde fraction boiling 
at 110 - 112° C. (12 m.m.) is a pale yellow oil with a very 
strong lemon odour like citral. When submitted to treat- 
ment with sodium sulphite by Burgess’s method, it is com- 
pletely absorbed, showing the absence of non aldehydic 
