243. STARCH, LICHENIN, ETC. 249 



poison. 1 It is precipitated by tannin and basic acetate of lead, 

 and from concentrated solutions also by chlorine-water and 

 phenol. It does not share with albuminoids the reactions men- 

 tioned in 92. 



On keeping ergot for any length of time, part of the sclerotic 

 acid appears to be converted into an allied substance containing 

 6 '6 per cent, of nitrogen, which has been named scleromucin. It 

 can be extracted with warm water, but requires less alcohol for pre- 

 cipitation than sclerotic acid. Diffused in water whilst still moist, it 

 forms a mucilaginous liquid ; but once dried, it is not dissolved by 

 cold water, and not with facility by warm. It resembles sclerotic 

 acid in its action and other properties. 



STARCH. LICHENIN, WOOD-GUM, ETC. 



243. Starch. Starch is not, as is well known, a homogeneous 

 substance, but it is nevertheless usual, and very properly so, to 

 estimate the whole of the carbohydrates of which it is composed 

 as directed in 113 to 115. Formerly three principal con- 

 stituents of starch were generally distinguished : first, one striking 

 a blue colour with iodine, and passing into solution when 

 starch is triturated with powdered glass and water soluble starch, 

 amidulin, s amylon (Bechamp) ; secondly, a substance character- 

 ized by its insolubility in cold water, solubility in saliva, etc., and 

 by the blue colouration it yields with iodine, granulose, the prin- 

 cipal constituent of all starch ; and thirdly, cellulose, which, in the 

 form of a membrane, gives to the starch grain its particular shape } 

 is coloured yellow by iodine (after boiling with water, violet), and 

 is converted by chloride of zinc into a substance that is tinged 

 blue by the same reagent. 



Some years ago Nageli 2 stated that in his opinion there ex- 

 isted two different modifications of amylon, which he called blue 



1 From 0'03 to 0'04 gram produces in frogs a swelling of the skin and almost 

 complete paralysis, commencing at the hinder extremities. Irritants produce 

 no effect, and indeed the animal gives no other sign of life than an occasional 

 feeble contraction of the heart. Although its condition may appear to improve 

 in the course of five to seven days, it sometimes succumbs to a relapse. 



2 Annal. d. Chem. und Pharm. clxxiii. 218, 1874 (Journ. Chem. Soc. xxviii. 

 55. See also Musculus, Annal. de chim. et de Phys. ii. 385, 1874 (Pharm. 

 Journ. and Trans. [3], v. 3) ; Musculus and Gruber, Journ. de Pharm. et de 

 Chim. xxviii. 308, 1878 (Journ. Chem. Soc. xxxiv. 778) ; Bondonneau, Repert. 

 de Pharm. iii. 231, 1875 (Journ. Chem. Soc. xxix. 365) ; Journ. de Pharm. et 

 de Chim. xxiii. 34, 1874 ; Bechamp, ibid. 141. 



