CELLULOSE 75 



up five grains of ground malt with 50 c.c. of cold water, and 

 after allowing it to stand for four hours, filter so as to get a clear 

 solution. 



Next grind some starch with water in a mortar and pour a little 

 of the mixture into a 200 c.c. flask of boiling water. When cool 

 pour about 20 c.c. of this thin starch paste into three test-tubes : 

 show the presence of starch by adding a few drops of the solu- 

 tion of iodine mentioned in Ex. 40 to one tube, and to the other 

 two tubes add 3 or 4 c.c. of the diastase extract, and warm 

 them to 60 C. Test for the presence of starch in one of these 

 two tubes by taking out at intervals of five minutes a few drops 

 with a pipette and adding them to weak solutions of iodine kept 

 in a series of test-tubes. 



After a time the starch is changed into sugar and dextrin : 

 When this has happened show the presence of the sugar by 

 means of Fehling's solution (Ex. 44). 



See if Fehling's solution is acted upon by the thin starch 

 paste when no diastase is added. 



() Cellulose. Somewhat allied to starch is cellulose 

 and its derivatives, which form the solid cell walls of 

 plant tissues : they are produced by the activity of the 

 protoplasm or living material within the cells. What 

 may be regarded as typical cellulose may be obtained 

 from cotton wool, paper, and flax fibre. It has an 

 empirical formula near C 6 Hi O 5 , is insoluble in water, 

 dilute acids or alkalis, but dissolves in ammoniacal cupric 

 oxide and other solvents. Cellulose usually stains blue 

 when treated with strong sulphuric acid and iodine. 

 Several complicated compound celluloses, such as the 

 ligno-celluloses of timber and the adipo-celluloses of 

 cork, are known, but these cannot be mentioned further 

 here. 



Hydrolysis and Fermentation of Cellulose. The cellu- 

 lose walls of the endosperm of many seeds are hydrolysed 



