484 LABIATE. 



if shaken with a concentrated solution of bisulphite of sodium. It is 

 worthy of note that oils of different origin, which cannot be distin- 

 guished by means of nitric acid, exhibit totally different colorations if 

 mixed with either of the liquids just named, or with vapour of bromine. 

 This behaviour may be of some use in the examination of commercial 

 sorts of peppermint oil. 



As to bisulphite of sodium, it yields a solid compound with certain 

 kinds of peppermint oil, which we have not yet examined. 



Production and Commerce — In several parts of Europe, as well 

 as in the United States, peppermint is cultivated on the large scale as a 

 medicinal plant. 



In England the culture is carried on in the neighbourhood of Mitcham 

 in Surrey, near Wisebeach in Cambridgeshire, Market Deeping in Lin- 

 colnshire, and Hitchin in Hertfordshire. 



At Mitcham in 1850 there were about 500 acres under cultivation; 

 in 1864 only about 219 acres.^ At Market Deeping there were in 1871 

 about 150 acres cropped with peppermint. The usual produce in oil may 

 be reckoned at 8 to 12 lb. per acre. The fields of peppermint at Mitcham 

 are level, with a rich, friable soil, well manured and naturally retentive 

 of moisture. The ground is kept free from weeds, and in other respects 

 is carefully tilled. The crop is cut in August, and the herb is usually 

 allowed to dry on the ground before it is consigned to the stills. These 

 are of large size, holding 1000 to 2000 gallons, and heated by coal ; 

 each still is furnished with a condensing worm of the usual character, 

 which passes out into a small iron cage secured by a padlock, in which 

 stands the oil separator. The distillation is conducted at the lowest 

 possible temperature. The water that comes over with the oil is not 

 distilled with another lot of herb, but is for the most part allowed to 

 run away, a very little only being reserved as a perquisite of the work- 

 men. The produce is very variable, and no facilities exist for estimat- 

 ing it with accuracy.^ It is however stated that a ton of dried 

 peppermint yields from 2|- to 3| pounds of oil, which equals Oil to O'lo 

 per cent. But we have been assured by a grower at Mitcham that the 

 yield is as much as 6 pounds from a ton, or 0'26 per cent. 



At Mitcham and its neighbourhood two varieties of peppermint are 

 at present recognized, the one being known as White Mint, the other as 

 Black Mint, but the differences between the two are very slight. The 

 Black Mint has 'purple stems ; the White Mint, green stems, and as we 

 have observed, leaves rather more coarsely serrated than those of the 

 Black. The Black Mint is more prolific in essential oil than the White, 

 and hence more generally cultivated ; but the oil of the latter is superior 

 in delicacy of odour and commands a higher price. White Mint is 

 said to be principally grown for drying in bundles, or as it is termed 

 " hunching." 



Peppermint is grown on a vastly larger scale in America, the localities 

 where the cultivation is carried on being Southern Michigan, Western 



1 Pharm. Joum. x. (1851)297. 340 ; also These they let to smaller cultivators who 



Warren in Pharm. Joiirn. vi. (1865) 257. pay so much for distilling a charge, i.e. 



To these papers and to personal inquiries whatever the still can be made to contain, 



we are indebted for most of the particulars without reference to weight. Hence the 



relating to peppermint culture at Mitcham. dried herb is preferred to the fresh, as a 



- Only the larger growers have stills. larger quantity can be distilled at one time. 



