CLOVES. 227 
its boiling-point 251°-254° C.; its optical power is very slightly 
levorotatory. The other, and the chief, constituent is Hugenol, 
C,)H,,0,, which exists to the extent of 76 to 85 per cent. in the 
oil. It has been found that very fine samples may contain as 
much as 90°64 per cent. of eugenol. 
Good oil of cloves should have a sp gr. of 1:067 at 15° C., and 
be freely soluble in alcohol of 90 per cent. An adulteration of 
turpentine would lower the sp. gr. and diminish the solubility in 
alcohol. 
Eugenol is a strongly refractive liquid with the characteristic 
smell and burning taste of cloves; by exposure to the air it becomes 
brown. On fusion with caustic potash it yields protocatechuic 
acid, and is convertible into vanillin by the action of potassium 
permanganate (see Vanillin). 
Besides forming the chief constituent of oil of cloves, it is found 
to a large extent in Allspice (Eugenia Pimenta), in the leaves of 
the Cinnamon-tree (Cinnamomum Zeylanicum), in Canella Bark 
(Canella alba), and probably in the Brazilian Cinnamon (Dycipel- 
lium caryophyllatum). It also occurs in the leaves of Illicium 
religiosum and of Laurus nobilis. It has been produced artificially 
by the action of sodium amalgam on coniferyl alcohol *. 
Pure eugenol has a sp. gr. of 1072 at 15°C. Its boiling-point 
is 253°-254° C., and it forms a clear solution in a 1 per cent. 
caustic-potash solution. 
The market value of an oil of cloves being dependent on the 
amount of eugenol contained in it, it becomes necessary to quanti- 
tatively estimate that amount. 
The usual method of separating eugenol from oil of cloves is by 
shaking up three parts of the oil with a solution composed of one 
part of caustic potash or soda in ten parts of water, pressing the 
crystalline paste of eugenol alkali that forms, taking up the press- 
residue with water, decomposing with hydrochloric acid, washing 
the liberated eugenol with water, drying it with calcium chloride, 
and then rectifying. 
A more simple process for determining with accuracy (at least 
to within 1 per cent.) the amount of eugenol, has been recom- 
mended by Thoms, in a paper read at the meeting of the “ Society 
of Naturalists and Physicians” in Halle +. The oil is converted 
* Ber. Deutsch. chem, Ges. ix. p. 418. + Pharm. Centralhalle, Oct. 8, 1891, 
Q2 
