WITCH-HAZEL 255 



even when present in small proportion (1 : 200,000) only. With concentrated 

 sulphuric acid they produce a characteristic red coloration ; with a mixture 

 of alcohol and sulphuric acid and ferric chloride a green colour is 

 obtained. 



The saponins have been classified in two series, viz. acid saponins (quillajic 

 acid, polygalic acid, guaiacsaponic acid, &c.) and neutral saponins (quillaja- 

 sapotoxin, senegin, parillin, guaiacsaponin, &c.). The composition of many 

 of them may be expressed by the general formula C w H 2w _ 8 10 (Kobert) ; for 

 neutral saponins of the formula C 17 H 26 10 the name of sapotoxin is reserved. 



Commercial saponin is usually obtained from quillaja bark, and is a mixture 

 of quillajic acid, quillaja-sapotoxin, and frequently also a non-toxic modification 

 of quillajic acid produced during the preparation ; as the term saponin has 

 become a generic one, a prefix to indicate the source would be desirable. 



Quillajic acid, C 19 H 30 10 , has been obtained as a colourless amorphous mass, 

 the powder of which is strongly sternutatory. The aqueous solution is acid 

 and has an acrid taste. Boiled with a mineral acid it yields quillaja-sapogenin, 

 galactose, and another sugar, which is non-fermentable and dextrorotatory. 



Quillaja-sapotoxin, C 17 H 26 10 , is also white, amorphous, sternutatory, and 

 acrid. 



. Quillaja bark has been recommended as a stimulant and 

 expectorant, but has not met with much favour. A tincture is largely 

 used as a means of emulsifying tars, &c. 



Substitutes. A quillaja bark differing from the foregoing in being 

 thinner and in having a more or uniform, distinctly reticulated outer 

 layer has been imported ; its botanical origin is unknown (possibly 

 Q. Poeppigii, Walp.). Another variety in quills 7 to 15 cm. long, 

 1 to 2-5 cm. wide and about 3 mm. thick, softer and not laminated, 

 has been referred to Q. smegmadermos, de Candolle. 



WITCH-HAZEL BARK 



(Cortex Hamamelidis) 



Source, &C. The witch hazel, Hamamdis virginiana, Linne (N.O. 

 Hamamelidece), is a common shrub in the United States and Canada. 

 It attains a height of about 3 metres and resembles the common hazel 

 both in its leaves and its fruit, which is edible. The bark should be 

 coUected in the spring. 



Description. Witch-hazel bark occurs in thin channelled pieces 

 of a characteristic, pale reddish pink colour, occasionally as much as 

 15 or 20 cm. long and 2'5 cm. wide, but usually much smaller. They 

 are sometimes covered with an ash-grey smooth cork which in older 

 pieces becomes darker in colour, fissured, and scaly. Frequently the 

 cork has been removed and the cortex forms the outer layer, which 

 is then pale reddish brown in colour and nearly smooth, exhibiting 

 under the lens slight transverse striations. 



