ANISE. 163 



congelation. They are marketed as distinct oils, and Dealers by 

 practise can readily distinguish one from the other by the sense of 

 smell alone. 



The earliest scientific examinations of oil of anise were made by 

 Cahours* and Gerhardt ;f also by Kraut & Schlam.J 



It was formerly considered that the congealing point of oil of 

 Pimpinella Anisum was 50^ to 59 '^ F. (10^ to 15° C.) and that of 

 " Star Anise " 35°-6 F. (2*^ C.) ; these figures are authoritatively 

 given in " Pharmacographia " and the French translation of the 

 same ; in the Pharmacopcneia Brit. 1885, and in the United States 

 pharmacopeia, but it is now ascertained and acknowledged that 

 those figures are abnormal and that the t7'ue congealing point of 

 oil of Piminnella Anisum is the same as that of oil of " Star 

 Anise," viz., 15"^ C. (59° F.). The cause of this rectification of 

 figures is owing to the discovery that the original observer, 

 Cahours, in determining these congealing points, must have over- 

 looked or omitted to take note of tlic laiu of heat of congelation, and 

 recorded the congealing points by exposing the oil at rest to the 

 low temperature, but with the thermometer not actually immersed 

 in the fiuid. Further, — that the authors of the works above 

 referred to, and of all other text-books, have accepted Cahour's 

 determination as correct, without verifying it by experiment. 



Of course if Cahour's specimen was adulterated or was not 

 virgin, i.e., if part of the anethol had been abstracted from it, or if it 

 had suffered change by oxidation, the uncongealable portion would 

 be in excess of the normal quantity and so hold the remaining 

 anethol in solution at a low temperature, but his Memoire states 

 that commercial oil holds more than four-fifths of anethol. The 

 error and its source was pointed out by Umney in a Paper read at 

 an Evening Meeting of the Pharmaceutical Society, 13th February, 

 1889. § He there drew attention to the well-known fact that some 

 liquids, such for example as water, saline solutions, &c., when at 

 absolute rest, are capable of being cooled many degrees heloiu their 

 normal ]point of congelation without hecoming solid. But when a 

 liquid solidifies after being cooled below its normal freezing point, 



* Ann. de Cliini. and de Phys. [3], ii., p. 274 ; Compt. Rend, xx., p. 53. 

 + Compt. Rendus des travaux de Chimie, 1854, p. 65. 

 X Zeitsch. Ch. Pharra., 1863, p. 359. 

 § Pharm. Jouru. [3], xix., 647. 



