THE TECHNOLOGIST. [Feb. 1, 1865. 



314 ON THE CULTIVATION OF 



informed me he cultivated entirely for distillation, and which as dried 

 flowers he had a difficulty to dispose of. I could see no difference, 

 further than the flowers were fuller and more expanded. It is not im- 

 prohahle that the oil receptacles might have an abnormal development 

 by manuring and particular care. I do not believe that it is a distinct 

 variety. The yield of oil per acre from this kind is 8 lb. 



The yield of chamomile flowers per acre is about 4 cwt. 



Pennyroyal yields about 12 lb. of oil per acre ; and so extremely 

 variable is this plant in its yield of oil, that one grower informs me that 

 he obtained only five ounces from a quarter of an acre : of course, he 

 ceased to cultivate pennyroyal for distillation. 



The Provence rose is extensively cultivated for the production of 

 rose-water ; large quantities are also dried for the London markets. The 

 damask rose is cultivated by a feW growers for drying, and is never 

 distilled. During a favourable season, 300 bushels of roses are produced 

 per acre. 



If all the lavender and peppermint cultivated were distilled, the 

 amount of oil supplied by Mitcnain will be about 2.190 lb. ol. mentliEe 

 pip., and about 2,060 lb. ol. lavand. ; but as a considerable quantity of 

 lavender is " bunched" and dried, the amount of oil supplied must be 

 much less. Between 30,000 and 40,000 bushels of roses are annually 

 produced in Mitcham, and about eleven tons of chamomile flowers. 

 Great care is taken in gathering and drying these flowers. The roses are 

 collected before sunrise. They are dried in ovens heated by air, and 

 are maintained at a constant temperature of 100° F. by a regulating 

 arrangement. After the chamomiles are dried they are " picked." This 

 operation consists in separating the darker flowers. The "bunched" 

 plants are dried in open sheds, secluded from the action of direct sunlight. 



The stills are of very large capacity, holding from 1,000 to 2,000 

 gallons. A charge occupies from six to eight hours. The distillation is 

 conducted at the lowest possible temperature ; and, as soon as the con- 

 tents of the retort have reached the boiling-point, the fire is withdrawn. 



The finest portion of the oil comes over during the first period of 

 distillation, and the receiver is exchanged. Only two qualities of oil 

 are generally collected and the receivers are exchanged after three hours' 

 run. There is a peculiar fragrance and delicacy in the oil first obtained, 

 which is decidedly wanting in the product which comes over towards 

 the end. 



I find that a much less proportion of camphor exists in the Mitcham 

 oils than in oils generally. This might be due to their freshness, and to 

 the peculiar alchemistical notions of the distiller of conducting every- 

 thing in the dark. No doubt, exclusion from the actinic rays is as 

 desirable fur the preservation of essential oils as other products of the 

 vegetable kingdom. The oils generally are of very light specific gravity, 

 and their refractive power is very great. 



In operating with such large quantities of water, involving as it 



