366 ODOROGRAPHIA. 
operation goes on as before, and can proceed contiauously until 
the whole crop be distilled. On large plantations it may be more 
convenient to employ several small stills than one large one. 
The process of distillation by driving dry steam through the 
flower is quite unsuitable to this flower as it scorches the oil. 
Freshly distilled oil has a herby odour, but if put away im a 
cool place in the dark and the bottles be left wacorked and loosely 
covered with cotton wool to keep out dust, these odours will pass 
off in about three months. The herby odour is partly due to 
particles of water of vegetation being held in mechanical suspension 
or in solution; this may be removed by drying the oil with calcic 
chloride. The fine mellowness of matured oil is the result of 
chemical change *. 
Spirit of wine should not be added to new oil; it would cause a 
slight etherification of very rancid odour. 
Stocks of oil should always be kept in one uniform low tempe- 
rature, inadark place. The newly distilled oil is almost colourless, 
or very pale straw-colour when viewed in bulk. It improves or 
mellows by keeping, and is then catalogued as “ matured” oil, 
with date affixed. This improvement is distinctly noticeable 
during the first five years; after which, it has a tendency to 
deteriorate by oxidation and resinification ; this may be prevented 
by admixture with 20 per cent. of grape-spirit of 60 o.p. 
Redistillation, or rectification, is said to improve the quality ; 
but this is very questionable. The less it is submitted to the 
action of heat the better. However, if necessary to rectify it, 
the first step would be to wash it thoroughly by agitation with an 
equal volume of cold water to which a little carbonate of magnesia 
had been mixed; allow it to rest in a cool place to separate, then 
draw off the supernatant oil and distil it with an equal bulk of fresh 
water, the heat being applied by a steam-jacket, and the distillate 
collected in two portions, the first four-fifths being retained and 
the remainder kept apart as inferior. It may also be rectified by 
Dragendorfi’s process. (See Rosemary, p. 373.) 
Pure English oil of lavender consists of a mixture im variable 
proportions of an oxygenated oil and a hydrocarbon Cy)Hy,, and 
* It has recently been discovered by Raoul Pictet that the mellow flavour 
and fine bouquet observable in old brandy can be rapidly produced in young 
brandy by subjecting it to the action of intense cold (produced by the sudden 
evaporation of methyl-chloride). 
