106 LABIAT.K 



Dr. Hermann Wolff {Therop. Mannish., 1890, j?fo. {>) lias 

 exhaustively reported on his experience of two years with the 

 treatment. In India it is chiefly used as a stimulant carmina- 

 tive by vegetarians in the same manner as the essential 

 oil of peppermint, which is largely imported from China 

 and Japan. One of us has found a large rectal injection of 



peppermint m warm water afford 



renal colic. 



Description. — Chinese oil of pepijermint is generally 



higli coloured and very 



after-taste. It 



be 



able to compete with the Japanese oil which has nearly driven 

 it from the Indian market. The menthol of China and Japan 

 occurs in long hexagonal crystals, resembling sulphate of mag- 

 nesium, which contain much water. E. B. Kyle [Amer. Jo urn. 

 ofPharm., 1885) mentions the following among the properties 

 of menthol. When thrown upon water, currents are produced to 

 and from the dissolving crystals. Menthol liquifies with chloral, 

 thymol, and camphor ; and this action is particularly noticeable 

 with thymol, crystals of the two substances placed in contact 

 being in a few minutes transformed into a thick oily liquid. 

 On gently heating a mixture of 1 drachm of the aqueous solu- 

 tion of menthol with half a drachm of a solution of 1 grain of 

 iodine and 5 grains of potassium iodide in two drachms of water, 

 with a small quantity of potash solution, the characteristic odour 

 of iodoform is developed. The aqueous solution is not affected 

 by ferric chloride or bromine water, but yields a slight turbidity 

 ^■ith chlorine water. One grain of menthol yields, with 120 

 drops of sulphuric acid, a brownish red liquid of a very dis- 

 agreeable odour, and on the addition of a Uttle potassium bichro- 

 mate becomes chrome-green, the colour remaining unaltered 

 for several weeks. Menthol slightly warmed with nitric acid 

 yields a thick, wine-coloured, oily liquid, and at a higher 

 Heat red fumes are given off; on neutralizing now with ammonia, 

 a precipitate is observed which is soluble in alcohol, and the 

 solution when evaporated yields an indistinctly crystalline 



ina>is. 



