256 



CELLULOSE, LIGNIN, ETC. 



as a special chemical compound (gluco-lignose, gluco-drupose of 

 Erdmann). Erdmann assumes that it is decomposed by hydro- 

 chloric acid with production of glucose, together with lignose or 

 drupose, and that with nitric acid it yields cellulose, whilst the 

 lignose or drupose undergoes further decomposition. Bente, 1 

 who doubts the existence of gluco-drupose, shows that wood-cells 

 (? lignin) yield pyrocatechin when fused with potash. 



248. Cellulose. The cellulose obtained from various plants 

 in the manner indicated does not appear to be invariably of the 

 composition C 6 H 10 5 . That isolated by Stackmann from coni- 

 ferous wood was represented by the formula 5(C 6 H 10 O 5 ) + H 2 0, 

 and the cellulose that certain sclerenchymatous and bast-tissues 

 yielded to Koroll was of similar composition. The latter chemist 

 also prepared it from parenchymatous tissues, and then it generally 

 possessed a composition approximately indicated by the formula 

 5(C 6 H 10 O 5 ) + 2H 2 O, whereas the wood of most dicotyledons 

 contains, according to Stackmann, a cellulose of the formula 

 5(C 6 H 10 5 ) + 3H 2 0. In these experiments the substance was 

 exhausted with water, alcohol, dilute soda, dilute acid, a mixture 

 of one part of sulphuric acid with four of water, and chlorine- 

 water, previously to being treated with nitric acid and chlorate 

 of potassium. Schuppe has shown that the action of the 

 sulphuric acid, the use of which I recommend to be discontinued, 

 results in the formation of a hydro-cellulose. If the treatment 

 with sulphuric acid was omitted, the cellulose obtained from 

 woods corresponded in composition to the formula C 6 H 10 5 . But 

 the cellulose isolated from apples by a process that did not in- 

 clude treatment with sulphuric acid showed a deviation in com- 

 position from the formula C 6 H 10 5 . 2 



The cellulose of fungi (cf. 249) frequently shows a com- 

 position corresponding almost exactly to the formula C 6 H 10 5 . 



249. Varieties of Cellulose. The variations observed in celluloses 

 isolated from different plants is partly to be ascribed to the above- 

 mentioned difference in composition, and partly probably to varia- 

 tions in density. For instance, the cellulose of most phanerogams 



1 Annal. d. Chem. und Pharm. cxxxviii. 1, 1866, and Jahresb. f. Pharm. 

 9, 1867. Compare also Bente, Ber. d. d. chem. Ges. xiii. 476, 1875 ; Journ. 

 f. Landwirthsch. 166, 1876. Compare also Bevan and Cross on the chemistry 

 of Bastfibre, Chem. News, xlii. 77, 91, 1880, 



2 Compare the dissertations of Pfeil and Treffner already quoted. 



