96 LIGNIN, CELLULOSE, ETC. 



sulphite of soda (1 in 32), "washes M-ith alcohol, and finall}' removes 

 to a dilute alcoholic solution of acetate of rosaniline (1 in 960), 

 the excess of which is washed out with spirit. Aniline-blue is 

 said to impart a fine blue or violet colour to the parenchyma of 

 the medullary rays, etc. The solution is made by dissolving 

 0'0325 gram of aniline-blue in 3 "88 gram of water, adding 

 0*5 gram of strong nitric acid and spirit to 48 grams. After 

 staining red as directed by Stiles, the section may be immersed 

 for a few minutes in the solution of aniline-blue, washed with 

 spirit and finally treated with cajej^ut oil or turpentine. 



Wiesner^ has described a qualitative reaction for woody tissue, 

 which consists in moistening the section with a 0*5 per cent, 

 solution of phloroglucin, and subsequently treating with hydro- 

 chloric acid. The lignified tissue assumes a reddish or violet colour. 



§ 117. Estimation of Cellulose. — The residue, after treating as 

 directed in § 116 and weighing, is a mixture of cellulose, inter- 

 cellular substance, remains of the cuticular substance, etc., together 

 with a little ash (and possibly also sand). It may be removed 

 from the filter (which should be reserved), powdered, and 

 introduced into a flask containing 50 to 100 cc. of nitric acid 

 (sp. gr. 1*16 to 1*18) ; 1 to 2 grams of chlorate of potash are then 

 added, and the mixture allowed to stand in a cool place with 

 occasional agitation until the insoluble matter appears almost 

 white. If this is not effected in a day or two the mixture may 

 be warmed for one or two hours to about 40° C. (not higher), and 

 again allowed to stand. If this is not successful the strength of the 

 nitric acid may be increased until it reaches a specific gravity 

 not exceeding 1 -20. After the action of the acid has been continued 

 long enough, it may be diluted with water and filtered, taking 

 care to pour the supernatant liquid on to the filter, leaving the 

 insoluble matter as long as possible in the flask. After washing 

 free from acid, it is treated with dilute ammonia (1 in 50 of 

 water) as long as that is coloured broAvnish, and finally with 

 alcohol and, if necessary, with ether. The residue is dried and 

 weighed. The loss in weight usually represents intercellular 

 substance and certain carbohydrates allied to cellulose, but less 

 resistent (hydrocelluloses), etc. (See §§ 245, 246.) The residue 

 on the filter consists of cellulose with a little ash (silica, sand, 

 etc.), that may be estimated and deducted. (See also § 248.) 



1 Zeitschr. f. anal. Chem. xvii. 511, 1878 (Journ. Chem. Soc. xxxiv. 612). 



