6 



BULLETIN 442, V. S. DEPAETMENT OF AGBICULTUE'E. 



charge. Drjmig the plants seems to have no effect on the citral 

 content of the oil, but on storing it was found that the solubiUty of 

 the oil in alcohol diminished more rapidly in the oils from the dried 

 material. 



T.\BLE II. — Yield nml citral rnntenf of lemon-grass oils f/istilled from green anfJ from 



flricfl plants. 



Condition of material. 



Weight of 

 material 

 f green). 



Weight of 

 material 

 (dried). 



Yield of 

 oil (based 



on green 

 weight of 

 material). 



Citral con- 

 lent of 

 the oil. 



Fresh 



Pounds. 

 78.1 

 9.3.1 

 100. 3 



Pounds. 



Per cent. 



0.37 



.31 



..32 



Per cent. 



7S 





.58. 3 

 62.7 



78 





79 









DISTILLATION. 









The apparatus required for the distillation of lemon-grass oil does 

 not differ from that in general use for the distillation of other volatile 

 oils. Before distilling the plants it has been found advisable to run 

 them through a fodder cutter, in order to permit closer packing in the 

 retort. From the data at hand it is estimated that if the plants are 

 cut into 2-inch lengths a retort will hold 100 pounds of material for 

 every 6 cubic feet of space, but if the plants are put in whole the 

 quantity which the retort can hold will be somewhat less. The 

 closer packing, how^ever, in no w^ay faciUtates distillation. 



In a retort having a capacity of 30 cubic feet a charge of 3,000 

 pounds can be distilled in 2 to 2 J hours by the steam which may be 

 readily generated in a small farm boiler, and by the use of a larger 

 volume of steam the time can be much reduced. 



In this connection it is interesting to note that distillation under 

 20 pounds pressure in the retort increased the yield of oil, but gave 

 an oil of very dark color and with lower citral content. 



After the oil has been distilled it should be freed from water so far 

 as possible in a separator}^ funnel, then dried by shaking with anhy- 

 drous calcium chlorid, and filtered. It should be stored in well-filled 

 air-tight containers in as cold a place as possible until ready to be 

 shipped to market. The shipping can be done in new and clean tin 

 cans wdthout injury to the product. 



In order to determine whether any appreciable quantity of oil 

 would be lost by discarding the distiUed water coming over w4th the 

 oil, a series of tests was made in 1915. The water from a number of 

 charges of several pounds each was retained and each lot separately 

 recUstiUed. In the apparatus used in the experiments about 1 

 gallon of water was secured for each 22 pounds of herb in the charge. 

 The average of the results secured bv tlie redistillation of this water 



