CLOVES 



467 



Constituents. The chief constituent is the volatile oil, which 

 occurs to the extent of 15 to 20 per cent, and consists of caryophyllene 

 and eugenol, the latter constituting 50 to 85 per cent of the oil. 

 The darkening of old oil of cloves is supposed to be due to furfurol, 

 an aldehyde formed on decomposition of some of the carbohydrates 

 and albuminoids. Cloves also contain an odorless, tasteless principle 

 caryophyllin, which crystallizes in silky needles and yields upon the 

 addition of fuming nitric acid crystals of caryophyllinic acid; vanillin; 



FIG. 202. Powdered Cloves: B, bast fibers; A, cells of anther showing the char- 

 acteristic markings or thickenings of the walls; P, pollen grains which appear 

 triangular in outline when mounted in water; 0, oil secretory cavities, the 

 large one to the left being from a petal; E, surface view of epidermal cells 

 of petal; P, parenchyma; C, calcium oxalate; T, tracheae; St, a number of 

 stone cells from the young branches or twigs, the so-called " clove stems." 



eugenin (isomeric with eugenol or eugenic acid), which resembles 

 caryophyllin but becomes reddish with nitric acid; gallotannic acid 

 10 to 13 per cent; calcium oxalate, and 5 to 7 per cent of ash. 



Cloves are the dried flower buds of Caryophyllus aromaticus L. 

 They contain not more than 5 per cent of clove stems, not less than 



