LAUKACE^l 131in 100 c.c. of water, and the alkaline sulphate produced is precipitated
by the addition of 100 c.c. of alcohol. After filtration the solution is
warmed, 9 grms. of oxamaethane are added in small portions, the whole
warmed for half an hour and allowed to cool. The azide separates in
crystalline tables, and these are separated and recrystallised. To esti-
mate the aldehyde by means of this reagent, a small quantity, not more
than 0*2 grm., of the oil is well shaken in 85 c.c. of water, and about
0
- 35 grm. of semioxamazide in 15 c.c. of hot water is added and the
whole well shaken. After five or ten minutes the compound begins to
be precipitated, and after standing twenty-four hours can be collected
on a Gooch filter, washed with cold water, and dried for a few minutes
at 105°. The amount of the precipitate is multiplied by 06083 to obtain
the amount of aldehyde. The constitution of the semioxamazone of
cinnamic aldehyde is NH 2. CO. CO. NH. N : CH. CH: CH. C 6 H 6.
The main constituent to which the odour of this oil, and of oil of
cinnamon, is chiefly due, is cinnamic aldehyde. Small quantities of
cinnamic acid, its oxidation product, are naturally found in the oil, the
amount varying according to its age. A terpene, and the acetic esters of
cinnamyl and phenyl-propyl alcohols, also exist in very small quanti-
ties. A stearoptene was also found in this oil in 1850 by Kochleder.
According to this chemist its formula is C 28 H 29 O 5. But a recent in-
vestigation by Bertram and Kursten^1 shows that it is ortho-methyl-
coumaric aldehyde C 6 H 4 (OCH 3 )(CH :CH. COH).
Dodge and Sherndal^2 have recently shown that cassia oil yields at
least 05 per cent, of constituents removable by shaking out with 2 per
cent, sodium hydroxide solution. The oily liquid obtained by liberating
these alkali-soluble constituents in the usual manner was found to con-
sist of approximately 25 per cent, of salicylic aldehyde; 60 per cent, of
coumarin; from 8 to 10 per cent, of cinnamic acid ; with small amounts
of salicylic and benzoic acids, and of a liquid acid not yet identified.
Although the amounts of salicylic aldehyde and of coumarin are small,
they are sufficient to contribute to the composite aroma of the oil. In
fact, the presence of salicylic aldehyde may be detected, by odour alone
in the first fractions of the redistilled oil. It is to this constituent that
the purple colour reaction is due, which is obtained when cassia oil is
shaken with dilute alkali and the acidified aqueous portion is treated
with ferric chloride.
The same chemists have since^3 shown that very small amounts of
benzaldehyde and methyl-salicylic aldehyde are also present in the oil.
Cassia oil, being packed in lead containers, usually contains traces of
lead, and in some quarters a demand has arisen for a lead-free cassia oil.
For the determination of the lead the method proposed by Lubetti
4
yields
useful results.
5 c.c. of the cassia oil to be tested is diluted to 20 c.c. with 90 per
cent, alcohol;
5 or 2
5 c.c. of this solution is taken according as the lead
content is more or less than 0
025 per cent., which will be determined by
a preliminary test. This amount is pipetted into a 50 c.c. Nessler glass
of small bore (2
5 cm.) and diluted to about 20 c.c. with 90 per cent,
alcohol. A blank from lead-free cassia oil, obtained by distilling the
commercial oil, is prepared in a similar way ; 1 c.c. of ammonium sul-
phide solution is added to both glasses and standard lead solution (1
l
3 Jour. Prdkt. Chem., ii., 51 (1895), 316. 2Jour. Eng. Ind. Chem. (1915), 1055.
Jour. hid. Eng. Chem. (1918), 10,12,1005. *Jour. Soc. Chem. Ind., 1920, 35.