128 ORGANIC AGRICULTURAL CHEMISTRY 



two, three, four and five nitric acid groups are formed. A 

 mixture of these lower nitrates of cellulose is called pyroxylin 

 or soluble gun cotton. It is soluble in alcohol and ether. Such 

 an alcohol-ether solution of pyroxylin is known as collodion and 

 is used in photography. When pyroxylin is mixed with camphor 

 and heated, a plastic mass is obtained which can be molded into 

 various shapes. This is known as celluloid. It is inflammable, 

 but non-explosive, and is used in manufacturing a great variety 

 of small articles for ornamental and toilet purposes. 



EXPERIMENT STUDY XXV 



Cellulose 



(i) Examine some cotton fiber and some filter paper as examples 

 of practically pure cellulose. 



(2) Test solubility of cellulose in ordinary reagents and in Schweit- 

 zer's reagent prepared as follows : To a solution of copper sulphate 

 add sodium hydroxide until a heavy light blue precipitate is formed. 

 (Excess of the alkali will dissolve the precipitated cupric hydroxide 

 to a deep blue solution.) Filter the cupric hydroxide, and wash out 

 all excess alkali. To 10 or 15 c.c. of concentrated ammonium 

 hydroxide add the cupric hydroxide as long as it will dissolve in the 

 ammonia. The deep blue solution resulting is ammoniacal cupric 

 oxide, and is known as Schweitzer^ s reagent. 



(3) Parchment Paper. Dip a piece of filter paper into dilute sul- 

 phuric acid 1:1. Remove the paper immediately and rinse in run- 

 ning water until well washed. The oaper will be found to be tough 

 and transparent and gives a blue test with iodine. It is called parch- 

 ment paper. 



(4) Hydrolysis of Cellulose to Glucose. Shred up a little filter 

 paper and add it to 10 c.c. concentrated sulphuric acid. Allow to 

 stand until the paper is all dissolved. When all dissolved, pour the 

 acid solution into 200 c.c. of water. Test a little of the dilute solu- 

 tion with iodine solution. What does the test show? The product 

 is known as amyloid from amylum which is starch. Now boil the 

 dilute solution for a half hour or so, and test a Httle with iodine, and 

 another portion with Fehling's solution. What does the test show ? 



