64 LABORATORY WORK IN PHYSIOLOGICAL CHEMISTRY. 

 Distillation-residue B. 



Upon evaporation this can be shown to contain NH 4 C1 

 formed from the NH 3 of the putrefaction product and the 

 HC1 added in the manipulation. 



Distillate C. 



Contains indole and skatoie (see Conjugate Sulphates). 



The first distillation carries over skatoie; this may be 

 tested as follows: 



(a) To 2 c.c. add a drop of HNO 3 and a drop or two of 

 KN0 2 solution (2 per cent). Notice the turbidity. 



(6) Add some concentrated HC1 to some of the distillate. 



Try the succeeding tests with the main distillate (indole}. 



(a) Moisten a piece of pine wood with concentrated HC1 

 and dip it into the distillate. A cherry-red color appears 

 on the wood. 



(6) Legal's reaction. To a few c.c. of the distillate add 

 5 drops of a freshly prepared solution of sodium nitroprusside ; 

 then make it alkaline with 2 drops of NaOH. A violet color 

 results, which resolves itself into deep blue upon acidifica- 

 tion with glacial acetic acid. 



(c) Acidify the distillate with HN0 3 and add 2 drops 

 of KNO 2 solution (see Skatoie). A red precipitate of nitroso- 

 indole nitrate results. 



Distillate D. 



Contains phenol and p.cresol. (Make very faintly alkaline 

 with KOH and concentrate to a small volume.) 



For the reactions of phenol see p. 96. 



p.cresol gives with ferric chloride solution a dirty-green 

 coloration. 



