CASSIA. 217 
been allowed to run into the flask from a pipette, and have been 
warmed on a water-bath, the entire quantity of sodium bisulphite 
solution is not at once added, but small portions at a time, waiting 
after each addition until the solid mass first formed has become 
partly fluid. Proceeding in this way, the formation of the liquid 
compound of the cinnamaldehyde with sodium bisulphite is com- 
plete in 10 to 15 minutes if the proportion of aldehyde is high. 
In the presence of large quantities of non-aldehydous contents the 
estimation requires a correspondingly longer time.] | On observing 
the supernatant layer of clear oil above referred to, the flask is 
removed from the water-bath, allowed to cool, and filled up with 
the bisulphite solution (towards the end with great care drop by 
drop) till the oil has entirely risen into the neck and its lower 
limit accurately coincides with the lowest mark on the neck of the 
flask. This oil consists of the non-aldehydes, whose volume has 
to be subtracted from the 10 c. em. of cassia oil taken. The difference 
shows the amount of cinnamaldehyde in 10 c. em. of oil. Assuming 
that 2°7 c. cm. of oil were read off in the neck of the flask, then there 
were 2°7 c. cm. of non-aldehydes in 10 c. em. of cassia oil, or, in other 
words, the oil contained 27 per cent. of non-aldehydes and 75 per 
cent. of cinnamaldehyde. Strictly speaking these are volume and 
not weight percentages ; as, however, the sp. gr. of the non-alde- 
hyde in cassia oil (1-060 at 20° C.) almost exactly accords with 
that of cassia oil (1:059-1:061 at 20° C.), the actual difference is 
only small and of no practical importance. 
In carrying out the process some patience must be exercised and 
the operator must not be content with only a nearly complete so- 
lution of the curd. Not a single flock ought to be perceivable 
either in the oil or adhering to the sides of the flask, as otherwise 
an accurate reading off of the quantity of oil is impossible and an 
error of several per cent. may arise. If the bisulphite solution is 
turbid, it must be previously filtered *. If the curd will not dis- 
solve, although the flask has stood an entire day in the boiling 
water, an extraordinarily heavy adulteration of the cassia oil with 
a hard resin may be assumed. In this case a volumetric estima- 
tion of the cinnamaldehyde is impossible. When the oil is adul- 
terated both with resin and mineral oil (the most frequent and 
almost exclusive kind of adulteration) the separated non-aldehydes 
* Tt is necessary that the sodium bisulphite should have a sp. gr. of not under 
1:03 and that it be kept in well-stoppered bottles. 
