RADIX ARNICA. 391 



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

 17D0, 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 i^ootstock, an inch or two long, emitting from its 

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

 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 transverse 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-vasGular 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 Compositiojn — 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 Ar^iicine. He states it to possess 

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

 m alcohol or ether ; when neutralized with hydrochloric acid, it forms 

 a crystalline salt. 



The Arnidn extracted by Walz (1861) both from the root and flowers 

 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 arnicin the for- 

 mula C^'H-^0^ ; other chemists that of C^ff '0^ Arnicin has not yet 

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



Sigel (1873) obtained from dried arnica root about J 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 

 oodles, the principle being dimethylic ether of thymohydwquinone 



separates contains isohutyric acid, probably also a little angelic and 

 JorTnic acid ; but neither capronic nor caprylic acid, which had been 



pointed out by Walz. . ^ -, . 



A.rnica root contains inulin, which Dragendorff extracted from it to 



tne extent of about 10 per cent. 



Uses— Arnica 



as 



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 



1 Holmes in Pharm. Journ., April 11, 1874. 810. 



