22 THE PRODUCTION OF VOLATILE OILS AND PEEFUMERY PLANTS. 



This method has been largely displaced by the simple expression of 

 the oil. 



Owing to the ease with Avhich the peels of the fruits liberate the 

 oil, a method of expression is applied very conveniently to the sepa- 

 ration of the oil. Usually the peels from half sections of the fruit 

 are turned inside out and pressure brought to bear on the outer sur- 

 face in such a manner as to rupture a large majority of the oil vessels. 

 The oil thus liberated is collected upon a sponge, which absorbs it 

 and from which it is subsequently squeezed. By this method, known 

 as the " sponge method," the larger part of the oils of the lemon, the 

 orange, and the bergamot is extracted, the operation being carried on 

 usually at night, when other activities in the fruit work are at a 

 standstill. 



Expression by the sponge method is far from complete because of 

 inability to bring pressure upon every, portion of the peel; hence, 



after the " hand-pressed " oils, which 

 are generally conceded to be the best 

 grade, are obtained the peels are placed 

 in a power press or in a crude still and 

 the remaining oil is separated. This 

 latter forms a secondar}^ oil of com- 

 merce, generally considered to be much 

 inferior to the sponged oil. 



The use of a mechanical device for 

 rupturing lemons and bergamots and 

 for expressing the oil from them has 

 been introduced into some producing 

 districts of Europe. However, only a 

 Fig. 3.— ficueiie for lacerating the small percentage of the oils is extracted 



^eLoTel'" "Xtnl uT""' ■" ""'^ ^-"y- 'he sponge system being 



most usually adopted. 



Whether the process of steam distillation, which will be discussed 

 later, if somewhat modified would produce a grade of oil equal to the 

 hand-pressed oil is doubtful. At any rate, the oil containing only 

 traces of compounds capable of decomposition at the usual tempera- 

 ture of steam, it should not be greatly inferior, production by this 

 method would be easier, and its cost would be materially less. 



SEPARATION OF PERFUMES BY STEAM DISTILLATION. 



A simple still, which consists essentially of three parts, the still 

 body, the condenser, and the receiver, with a suitable means of ajoi^ly- 

 ing direct heat to the still body, containing material suspended in 

 water, was used early in the eighteenth century. Even at the present 

 time many smaller distillations are still carried on with this form of 

 apparatus. The chief disadvantage of this type of still lies in the 



195 



