LIGNIN 22/ 



dissolving out the hydrolysable carbohydrate and weighing 

 the residual lignin ; the latter substance, however, is also 

 attacked to some extent by the acid with consequent loss of 

 methoxyl and acetyl groups ; moreover, it is liable to retain 

 a certain amount of carbohydrate. The action of 42 per cent 

 hydrochloric acid upon the lignified material for eighteen hours 

 at the ordinary temperature was first suggested by Will- 

 statter and Zechmeister * ; subsequently this method was 

 modified by Hagglund ; f Konig and Rump | employ i per 

 cent hydrochloric acid under 6 atmospheres pressure for 

 six to seven hours. Ost and Wilkening,§ on the other hand, 

 recommend 72 per cent sulphuric acid in the cold until a 

 portion of the solution gives no precipitate with water ; the 

 whole mixture is then poured into ten times its volume of 

 water and the residual lignin is filtered off through cotton 

 wool. 



Methods of Estimating Cellulose in Lignified Tissues. 



Cross and Bevan's || method consists in exposing the 

 moist material to the action of chlorine for a short time,^ 

 whereby chlorination of the lignin complex results in the 

 formation of a lignone chloride to which they give the 

 formula Ci9Hig09Cl4. The lignone chloride is then dissolved 

 out by means of a 2 per cent solution of sodium sulphite 

 whereby a pink colour is produced which may be regarded 

 as a true colour reaction of the lignin complex ; the material 

 is then chlorinated again, and extracted with sodium sul- 

 phite and the process is repeated until a pink colour is no 

 longer produced by addition of the sulphite ; the number 

 of chlorinations required varies from two to five according 



* Willstatter and Zechmeister : " Ber. deut. chem. Gesells.," 191 3, 46, 

 2403. 



t Hagglund : " Arkiv Kemi, Mineral Geol.," 1918, 7, 8. 



t Konig and Rump : " Zeit. Nahr. Genussm.," 1914, 28, 177. 



§ Ost and Wilkening : " Chem. Zeit.," 19 lo, 34, 461. 



II Cross and Bevan : " Cellulose," 1895, p. 102 ; and " J. Chem. See," 

 1882, 41, 94. 



Tl Over-exposure leads to the chlorine attacking the cellulose with 

 formation of oxycellulose. See Heuser and Siebert : " Zeit. angew. 

 Chem.," 1913, 26, 801. 



15* 



