A JO WAX. 151 



of an inch in length ; in colour they are greyish brown, the largest 

 much resembling those of common parsley, but they are readily 

 distinguished from them by their rough surface and strong odour 

 of Thymus vulgaris when rubbed. 



Under the name of Semen Ammi, the small fruit of Ammi 

 majus Lin. and of Sison Amomicm Lin. have sometimes been 

 mistaken for, or substituted for those of true Ajowan, but they can 

 be easily recognised by the absence of small tubercles on their 

 surface. 



In India the seeds of Hyocyamus niger Lin. are called Khorasani 

 ajwan, but a very superficial examination is sufficient to recognise 

 them. 



The fruits of Ajowan yield rather over 3 per cent, of an agreeably 

 aromatic volatile oil of sp. gr. varying from O'OOO to 0"930 at 15° 

 C. A crystalline substance, C^ ^ H^^ ^ 0, identical with Thymol, also 

 distils over. The oil, after being rectified over calcium chloride, 

 yields, on being exposed to a temperature of 0*^ C, about 40 to 50 

 per cent, of this body. The fruits are distilled to an enormous 

 extent in Germany for the purpose of extracting it. It is obtained 

 in India by exposing the oil to spontaneous evaporation, and sold 

 in the Bazars of the Deccan under the name of Ajwain-Ka-phul, 

 or " Flowers of Ajwain " (see Thymol). According to Fllickiger 

 the sp. gr. of this thymol is 1'028, it is optically inactive ; its 

 melting point in small quantities is 44 '^ C. and in bulk 51'^ C. He 

 obser^"es that on again refrigerating it, it remains in a liquid state 

 for a considerable time, or until a crystal of thymol is thrown into 

 it. (Eespecting an error in the determination of congelation 

 points of such bodies, see the remarks on Anethol. 



The odour of the liquid constituent of oil of Ajowan is different 

 to that of the thymol. Its boiling point is 172*^ C. It is 

 considered to be an isomer of cymene G-^^ ^\a. (which see), and is 

 optically inactive. The crude oil also probably contains a small 

 quantity of the hydrocarbon C ^ ^ H ^ g . 



The medicinal uses of Ajwan are described in the Bengal 

 Pharmacopoeia and in the Pharmacopoeia of India. The distilled 

 water appears to be particularly useful in cases of cholera. The 

 seeds themselves are much valued as a pungent aromatic for 

 culinary purposes, in fact in India this plant is considered one of 

 the most useful of the umbelliferous tribe. 



