Feb. 1, 1865.] THE TECHNOLOGIST. 



MEDICINAL PLANTS AT MITCHAM. 315 



must some considerable loss of oil, a plan was tried, some time ago, to 

 economize this unnecessary consumption of the oil, by using the impreg- 

 nated water for successive charges of the retort, but the expense of 

 pumping and storing away this water was greater than the loss arising 

 from the solution of the oil. 



The extracts obtained from belladonna, foxglove, stramonium, hen- 

 bane, poppies, and elaterium, cultivated at Mitcham, are in their 

 action and appearance very good. 



In the laboratory of Mr. William Hooper these cultivated plants 

 have been very extensively consumed ; and there can be no doubt but 

 that the uniformity of these extracts, as regards their medicinal ac- 

 tivity, is due in part to cultivation ; but it must not be overlooked that 

 the process by which these extracts are obtained is calculated to preserve 

 the activity of the plant, — for extractive matter, if oxidized, ceases to be 

 soluble. 



The soil of Mitcham is generally a good holding one, that is, retains 

 moisture well, and is naturally rich. It varies in depth even on the 

 same estate, being in some places only a few inches, whilst in others it 

 is several feet. 



Most growers supply large quantities of manure to their land, but 

 evidently do not supply the elements abstracted by the growing crops, 

 as the yield is continually diminishing. They do not lay out for two 

 successive seasons the same plants on the same ground. This is 

 axiomally admitted by them to be as desirable as the rotation of agricul- 

 tural crops. Some growers plant potatoes, &c, after peppermint ; and after 

 renewing the soil with manure, again plant peppermint. This plan is 

 considered highly beneficial to the production of crops. 



The uncertainty of the seasons in England, and the introduction of 

 foreign produce, have considerably reduced the annual production of 

 Mitcham. A large farm, consisting of more than 1 ,000 acres, which 

 was a few years ago laid out with lavender, peppermint, roses, chamo- 

 miles, carraways, and henbane, is now employed entirely for the pro- 

 duction of cereal crops ; and most growers, rather than meet with the 

 disappointment of a failure, lay out a large proportion of their land with 

 culinary vegetables. 



The flowers obtained during a very dry season such as the past 

 yield a larger proportion of oil than the flowers obtained during an 

 ordinarj T summer ; but, from the combined effects of the frosts during 

 the latter part of May, less oil will be obtained this year than for years 

 past. The yield of oil of lavender will be from 4 lb. to 5 lb. per acre. 

 • I have intentionally omitted to include in this paper the analyses of 

 the soils, as I consider them more intimately connected with the phe- 

 nomena of cultivation when considered in reference to physiological 

 effects. 



