REACTIONS OF INULIN 119 



water, and thus may be distinguished from calcium phosphate 

 which may occur in cells in shapes similar to those of inulin. 

 These two substances may be further recognized by the fact 

 that sulphuric acid completely dissolves inulin, whereas it forms 

 with calcium phosphate insoluble calcium sulphate. The 

 following tests also may be performed, 



1. Green's Test. — Sections of the material, which have been 

 soaked for some time in absolute alcohol, are treated with a 

 saturated solution of orcin in strong alcohol, and then boiled 

 in hydrochloric acid. The masses of inulin disappear and a 

 red colour results. If phloroglucin be substituted for the 

 orcin, the resulting coloration will be reddish-brown. 



2. Molisch's Test. — The sections are treated with a 10 per 

 cent alcoholic solution of a naphthol, then a few drops of 

 strong sulphuric acid are added and the preparation warmed, 

 A deep violet coloration ensues, and the inulin is dissolved. 



These colour reactions are indicative of the formation of 

 sugar by the hydrolysis of the inulin by the acids employed 

 in the tests ; it is therefore important, before employing these 

 reactions, to make sure that no free sugars are present in the 

 material to be examined, and to wash the preparations 

 thoroughly with alcohol in order to remove them. 



Since inulin does not reduce Fehling's solution, this re- 

 agent may be employed to ascertain whether any reducing 

 sugars are present in the material before employing the above 

 tests for inulin. 



The following reactions may be carried out with a solution 

 of inulin, 



3. The addition of iodine solution gives with inulin a 

 brownish coloration. Since the solution of iodine is itself 

 brown, this test must be performed very critically. The follow- 

 ing method may be employed : dilute the solution of iodine 

 with water until it is a light brown colour, fill two test tubes 

 with this solution and add to one a drop of the inulin solu- 

 tion ; now compare the colour of the contents of the two test 

 tubes. 



This same reaction is also given by glycogen, when the 

 same procedure may be followed, 



4. Basic lead acetate gives with inulin, and also with gly- 

 cogen, a white precipitate. This test may be used to distin- 



