RADIX ARNICA. 391 



of 1788, but it soon fell out of notice, so that Woodville writing in 

 1790, remarks that he had been unable to procure the plant from any 

 of the London druggists. Of late years it has gained some popular 

 notoriety as an application in the form of tincture, for preventing 

 the blackness of bruises, but in England it is rarely prescribed 

 internally. 



Description — The arnic root of pharmacy consists of a slender, 

 contorted, dark-brown rootstock, an inch or two long, emitting from its 

 under side an abundance of wiry simple roots, 3, 4 or more inches in 

 length ; it usually bears the remains of the rosette of characteristic, 

 ovate, coriaceous leaves, which are 3- to 5-nerved, ciliated at the margin, 

 and slightly pubescent on their upper surface. It has a faintly 

 aromatic, herby smell, and a rather acrid taste. 



Microscopic Structure — On a ti*ansverse section, the rootstock 

 exhibits a large pith surrounded by a strong woody ring. In the 

 innermost part of the cortical layer, large oil-ducts are found corre- 

 sponding to the fibro-vascular bundles. Neither starch granules, inulin, 

 or oxalate of calcium are visible in the tissue. The rootlets are of a 

 different structural character, but also contain oil-ducts. 



Chemical Composition — Several chemists have occupied them- 

 selves in endeavouring to isolate the active principle of arnica. 

 Bastick described (1851) a substance which he obtained in minute 

 quantity from the flowers and named Arnicine. He states it to possess 

 alkaline properties, to be non-volatile, slightly soluble in water, more so 

 in alcohol or ether ; when neutralized with hydrochloric acid, it foiins 

 a crystalline salt. 



The Arniein extracted by Walz (1861) both from the root and flowei-s 

 of arnica is a different substance ; it is an amorphous yellow mass of 

 acrid taste, slightly soluble in water, freely in alcohol or ether, and dis- 

 solving also in alkaline solutions. It is precipitable from its alcoholic 

 solution by tannic acid or by water. Walz assigns to arniein the for- 

 mula C^H^O' ; other chemists that of C'H^O". Arniein has not yet 

 been proved a glucoside, although it is decomposed by dilute acids. 



Sigel (1873) obtained from dried arnica root about | per cent, of 

 essential oil, and 1 per cent, from the fresh ; the oil of the latter had a 

 sp. gr. of 0*999 at 18° C. The oil was found to be a mixture of various 

 bodies, the principle being dimethylic ether of thymohydroquinoiie 



Qiogia J QpTT3, boiling at about 235°. The water from which the oil 



separates contains isohutyinc acid, probably also a little angelic and 

 fomnfiiG add ; but neither capronic nor capryhc acid, which had been 

 pointed out by Walz. 



Arnica root contains inulin, which Dragendorff extracted from it to 

 the extent of about 10 per cent. 



Uses — Arnica is used chiefly in the form of tincture as a popular 

 application to bruises and chilblains ; internally it is occasionally pre- 

 scribed as a stimulant and diaphoretic. 



Adulteration — Arnica root has been met with^ adulterated with 

 the root of Geum urhanum L., a common herbaceous plant of the order 



^ Holmes in Pharm. Joum., April 11, 1874. 810. 



