RAISINS 97 



about from 4 to 6 per cent, of the aldehyde citral, C 10 H 16 O, the latter being the 

 chief odorous constituent of the oil. Other odorous constituents are citronellal, 

 geranyl acetate, linalyl acetate, octyl and nonyl aldehydes, &c. ' Terpeneless ' 

 essence of lemon is prepared by distilling off the terpene in vacuo, and consists 

 mainly of citral (50 per cent.) together with the above-mentioned esters and 

 aldehydes. 



Allied "Dings. Bergamot. The fruit of Citrus Bergamia, Risso, 

 cultivated in southern Italy and Sicily. The volatile oil is obtained 

 by rotating the fruits in a machine against sharp copper points, 

 collecting and filtering the mixture of volatile oil and cell sap and 

 decanting. The pulp is pressed and the juice used for the production 

 of calcium citrate or citric acid. The oil contains linalyl acetate (34 

 to 40 per cent.), c?-limonene and bergaptene. 



Lime. The fruit of Citrus Medico,, var. acida, Brandis (West 

 Indian Lime) or of Citrus Limetta, Risso (Italian Lime). The volatile 

 oil of the former has an odour of citronella and contains citral and 

 limonene ; that of the latter an odour of bergamot and has a com- 

 position similar to bergamot oil but contains less linalyl acetate (26 per 

 cent.). The pulp of both contains citric acid (about 7 per cent.). 



RAISINS 



(Uvae Passae) 



Source, &C. The grape vine, Vitis vinifera, Linne (N.O. Ampelidece) 

 is cultivated in numerous varieties in most of the warmer temperate 

 regions, particularly in central and southern Europe, California, and 

 Australia. 



When the grapes are ripe most of the leaves are stripped from the 

 vine, and the stalk of the bunch is cut half through or twisted ; the 

 grapes are then allowed to dry by the heat of the sun. This process, 

 which occupies two or three weeks, is often hastened by cutting the 

 bunch off when partially dried, sterilising the fruits by dipping them 

 into a boiling alkaline solution and drying on wicker trays in the sun. 



Description. The ovary of the grape vine is superior and two-celled, 

 each cell containing two ovules. As the fruit reaches maturity the 

 interior becomes pulpy, the dissepiment disappears, and the ripe fruit 

 may be regarded as a superior berry. It is usually ovoid or nearly 

 globular in shape, and varies in colour according to the variety. The 

 dried fruits are of a purplish black or brownish colour, and more or less 

 shrivelled. 



Constituents. Raisins contain in the palp dextrose (grape sugar) 

 and acid potassium tartrate, both of which may be found crystallised 

 in small granular masses in old raisins. The skin and the seeds contain 

 tannin, and the latter a fixed oil in addition. 



7 



