220 ODOROGRAPHIA. 



unequally serrated, and are, as well as the stems, glabrous ; floral 

 leaves all bractea-formed, rather longer than the whorls, and are, 

 as well as the calyces, hairy, or somethnes glabrous ; spikes 

 cylindrical, loose ; whorls approximate, or the lower ones are 

 distant. This plant is a native of the temperate parts of Europe. 

 It is found at the Cape of Good Hope and in North and South 

 America, but was probably carried thither from Europe. Two 

 varieties are described by Bentham,* the angustifolia with narrow 

 leaves and the crispa with curled leaves. 



The oil of spearmint of commerce is chiefly derived from 

 Mentha aquatica, var. crispa, Benth.,-|- Syn. M. crispa, Lin. 

 Spec, p. 805. The leaves of this variety are plicately curled, 

 lacerately toothed and on short petioles. It is figured by Nees in 

 his " Plantarum in horto Medico." Other varieties of 31. aquatica 

 are the ncmorosa (Syn. M. citrata Eeichenbach) " Iconographia 

 botanica," t. 977 ; hirsida, Hooker's " Continuation of Curtis' 

 Flora Londinensis" v., t. 166, and suhsjncata (Syn. M. palustris 

 plicata, Eeichenbach) Iconographia hot., t. 976. The yield of oil 

 from spearmint averages 1 per cent., or nearly 25 pounds weight 

 of oil per acre per annum. Over 100 acres of it were formerly 

 cultivated in Wayne County, New York State, but owing to the 

 low prices which have ruled in this article for many years, the 

 cultivation in America has been totally neglected, and has been 

 limited this year to little more than garden culture, the total area 

 of spearmint in the whole of Wayne County not exceeding 20 

 acres, representing an output of 400 lbs. as compared with 568 lbs. 

 in 1892 ; 1,101 lbs. in 1891, and 2,229 lbs. in 1890. 



Oil of spearmint has been examined by Trimble,^ and the result 

 of his investigations appears to confirm those made by Gladstone as 

 far back as 1864,§ viz., that the pure crude oil consists of a terpene 

 Cio H;^^ and carvol Cjo H^^ 0, which can be separated by 

 fractional distillation, and by precipitating carvol by means of 

 alcoholic ammonium sulphide. The result is a mass of beautiful 

 acicular crystals, readily purified by solution and recrystallisation 

 from hot alcohol, and, when pure, free from odour, composed of 



* Labiatum Genera anil Species, p. 174. 



t Ibid., p. 177. 



ij: Pharmaceutical Record, 1885, pp. 291 and 312. 



§ Journ. Chem. Soc. 



