216 ODOROGRAPHIA. 
reagent used, and, by shaking up with ether, can with ease be 
entirely separated from the watery solution. (Except the cimnamic 
acid.) 
“The cinnamic acid found in every cassia oil is determined in 
this process as cinnamaldehyde. As, however, even in very old 
oil, not so much as one per cent. of cinnamic acid was found, the 
error is insignificant.” 
Cinnamic acid may be removed by shaking the’ oil with hot 
sodium-carbonate solution, and the amount found deducted from 
that of the aldehyde found. Cinnamic acid can be identified by 
its melting-point 131° C. (the melting-point of pure cinnamic acid 
is 133°), and by the formation of benzaldehyde by oxidation with 
potassium permanganate. When the oil of cassia is heated with a 
solution of bisulphite of soda for the purpose of determining the 
aldehyde, the cinnamic acid is dissolved with it, forming, according 
to Valet*, phenylsulphopropionate of soda. The pure acid is 
easily soluble in water, and cannot be extracted with ether from 
the solution acidified with sulphuric acid, therefore, according to 
the manner of determining cinnamaldehyde, it is reckoned as 
aldehyde. 
A later Circular issued by the same Firm describes another pro- 
cess for the estimation of cinnamaldehyde as follows :—A specially 
manufactured glass flask is required, of about 100 ec. em. capacity, 
with a neck about 13 cm. long and 8 mm. internal width, which is 
divided into tenths up to 6 c. cm.; also a pipette of 10 c. cm. capacity. 
Ten c. cm. of the oil to be examined are measured with the pipette 
and allowed to run into the flask; the pipette is drained for a 
minute or two, and the last drops blown out with the mouth. The 
flask is then about three-fourths filled with a 30-per-cent. solution of 
bisulphite of sodium, and the curd that forms immediately shaken 
a few times, powerfully but carefully, without allowing a drop to 
spurt out. The flask is then placed in a hot-water bath. The 
whole is kept hot for several hours and occasionally agitated. It is 
sometimes kept hot for half a day and at least till the curd is com- 
pletely dissolved and there floats on the surface a layer of clear oil, 
sharply defined against the solution. [A stilllater Circular, dated 
October 189], says the results may be arrived at more quickly by 
a slight modification of the process :—After 10 c. em. of the oil have 
* Annalen der Chemie, cliv. p. 62. 
