FOLIA BUCHU. 109 



Those of B. serratifoUa and B. hetulina pre.sent but little variation. 

 Each kind is always imported by itself. Those of B. hetulina are the 

 least esteemed, and fetch a lower price than the others, yet appear to 

 be quite as rich in essential oil. 



Buchu leaves have a penetrating peculiar odour and a strongly 

 aromatic taste. 



Microscopic Structure — The essential oil is contained in large 

 cells close beneath the epidermis of the under side of the leaf. The oil- 

 cells are circular and surrounded by a thin layer of smaller cells; they 

 consequently partake of the character of the oil-ducts in the aromatic 

 roots of Umbelliferce and CovipositcB. The latter, however, are 

 elongated. 



The upper side of the leaf of Barosvia exhibits an extremely 

 interesting peculiarity.^ There is a colourless layer of cells separating 

 the epidermis from the green inner tissue (mesophyllum). If the leaves 

 are examined under alcohol or almond-oil the colourless layer is seen to 

 be very narrow, and the thin walls of its cells shrunken and not clearly 

 distingruishable. If the transverse sections are examined under water, 



• • -I • 



these cells immediately swell up, and become strongly distended, giving 

 off an abundance of mucilage, the latter being aiforded by the solution 

 of the very cell-walls. The mucilage of buchu leaves thus originates 

 in the same way as in flax seed or quince seed, but in the former the 

 epidermis is thrown off without alteration. We are not aware that 

 other mucilaginous leaves possess a similar structure, at least not those 

 of Althcea offi.cinaUs and of Sesanium which we examined.^ 



Chemical Composition — The leaves of B. hetulina afforded us by 

 distillation lo6 per cent, of volatile oil,* which has the odour rather of 

 peppermint than of buchu, and deviates the ray of polarized light 

 considerably to the left. On exposure to cold it furnishes a camphor 

 which, after re-solution in spirit of wine, crystallizes in needle-shaped 

 forms. After repeated purification in this manner, the crystals of 

 BarosDia Camphor have an almost pure peppermint odour; they fuse 

 at 85° C, and begin to sublime at 110° C. After fusion they again 

 solidify only at 50° C. Submitted to elementary analysis, the 

 crystals yielded us 7408 per cent, of carbon and from 9 to 10 per cent, 

 of hydrogen.* Barosma camphor is abiuidantly soluble in bisulphide 

 of carbon. 



The crude oil from which the camphor has been separated has 

 a boiling point of about 200° C, quickly rising to 210° or even higher. 

 That which distilled between these temperatures was treated with 

 sodium, rectified in a current of common coal gas and submitted to 

 elementary analysis, afforded us 7786 per cent, of carbon and lOoS 

 of hydrogen. The formula C^'^H^^O would require 7894 of carbon and 

 10'53 of hydrogen. 



Wayne's experiments'* appear to indicate that the oil also contains 



^ Fluckiger in Schweiz. WochejutcJiriJifur — Barosma serratifolia appears to be less 



Pkarm. Dec. 1873, with plate. rich, according to Bedford (1863). 



^ See also Radlkofer, Monographie der * Our supply of the substance having been 



Sapindaceen-Gattunj Serjania, Aliinchen, exhausted by two analyses we cannot re- 



1875, p. 100-105. gard the above figures as sufficient for the 



^ Messrs. Allen and Hanburys operating calculation of a formula, 



on larger quantities obtained 1-63 percent. ^ j^t^. Joum. o/Pharm. 1876. 19. 



