THYME. 147 



and 52^ C. to a colourless liquid. When once completely fused and 

 allowed to cool to the ordinary temperature, it will maintain itself 

 in the fluid condition for several days, but the contact of a crystal 

 will at once cause it to crystallise. Its boiling point is near 230^ C. 

 It dissolves sparingly in water, requiring at 15^ C, 1100 to 1200 

 parts for solution ; but is soluble in half its weight of alcohol, ether 

 or chloroform, in 2 parts of soda solution, sp. gr., 1'16, and freely in 

 benzene, carbon disulphide, glacial acetic acid and fixed and volatile 

 oils. Ammonia dissolves it but sparingly. The potash and soda 

 solutions are spoken of by some authors as chemical combinations, 

 but the following test will demonstrate them otherwise : — AVhen 

 shaken with ether, the thymol can be entirely removed and 

 obtained as a neutral volatile residue. 



When thymol is triturated with one half to ten times its 

 weight of camphor, a colourless, syrupy liquid is obtained. 

 According to Gerrard, the strongest aqueous solution of thymol 

 possible, is 1 in 1,000, and a solution of 4 grains of it in 

 a fluid ounce of alcohol is miscible with water w^ithout becoming 

 turbid ; 3 grains of thymol are dissolved by 1 grain of caustic 

 soda and 1^ grain of caustic potash. Solid fats, when heated, 

 are excellent solvents of thymol. A solution of 1 part of 

 thymol in 100 parts of warm glycerin remains clear. Thymol 

 is also soluble in 4 parts of cold sulphuric acid, the solution 

 has a yellowish colour, and on being gently heated, becomes rose- 

 red. On pouring this solution into 10 volumes of water, digesting 

 the mixture with an excess of lead carbonate, and filtering, the 

 liquid becomes violet-blue on the addition of ferric chloride. This 

 reaction is due to sulphothy molic acid, CioHj^^SO^. Hammarsten 

 and Eobert gave the following as the most delicate test by wdiich 

 one millionth of thymol may be detected : — Mix the liquid with 

 one half of its volume of glacial acetic acid, then with at least an 

 equal volume of sulphuric acid, and warm gently, when a bright 

 reddish-violet colour is produced which is not destroyed by 

 boiling. 



Gerrard states that in operating upon nine different samples of 

 commercial oil of thyme (so-called oil of Origanum), by means both 

 of caustic soda and refrigeration, he was nnable, except in one 

 doubtful case, to obtain the slightest trace of thymol, the inference 

 being that commercial oil of thyme does not contain thymol, that 

 body having been removed from it previous to putting it on the 



