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lemons, with which we have made several experiments in distilling. We 

 relate below the result of our experience with that method of manipulation 

 only which produced the best results: — 



The yellow layer of the peel, which contains the essential oil of the 

 lemon, is removed by peeling. The thin peel which is thus obtained is 

 shredded and bruised mechanically as small as possible. The oily paste 

 is liberally diluted with water and the resulting thin mass is distilled 

 without previous expression, at between 50 and 60 mm. pressure, until 

 the distillate contains not a drop more of oil. All indirect heating with 

 steam-jacket vapour during the distillation must be avoided, and only steam 

 of any desired pressure which passes directly into the liquid should be 

 used. It is not necessary to cohobate the resulting water of distillation; 

 it may be used instead to dilute the paste in the next distilling-operation. 



By this process we obtained from the lemons 0,3% by weight of oil 

 with a pure odour, possessing the following properties: — 



disc 0,8551, « D + 55°30' (« D of the initial 10°/o of the distillate +48°), 



citral 3,4%. 

 d U o 0,8547, « D + 56°22' (« D of the initial 10% of the distillate -f 50° 4'), 



citral 4,5%. 



The higher the distilling-temperature maintained, the more favourable 

 is the course of the distillation, and the easier it is to increase the out- 

 put, but at the same time the more the aroma of the oil suffers. On the 

 other hand, a low temperature ensures the purity of odour of the oil, but 

 it also renders the evaporation more difficult, with the result that a smaller 

 proportion of oil, and especially of the less volatile citral, distils over. 

 The most favourable temperature is perhaps about 50°, or (when the 

 temperature of the condensing-water is over 20°) nearer 60°. 



Care should be taken to render the distilling apparatus, the condenser 

 and the receivers, as nearly air-tight as possible in order to prevent the 

 air-pump from sucking up too much air through the apparatus, and thus 

 to cause the wastage of oil by volatilisation. For it must be remembered 

 that every gallon of this air is also charged with a gallon of oily vapour 

 saturated at the temperature of the water of condensation, and that this 

 oily vapour is lost. 



Owing to the low distilling-temperature the cell-walls of the raw 

 material inside the still retain their natural turgescence for some little 

 time, a circumstance which greatly retards the liberation of the oil frony 

 closed cells; hence it is absolutely necessary to disintegrate the peel so 

 thoroughly that every cell is opened. 



A yield of 0,3% equals more than twice that obtained by hand-pressing. 

 We believe, however, that with some experience it will be possible to 

 increase still further the output of oil by our process. With water-distil- 

 lation under diminished pressure the less volatile constituents, especially 



