106 PHYSIOLOGICAL A.ND PATHOLOGICAL CHEMISTRY. 



melts, at first without decomposition (melting-point 187). 

 When heated more strongly the melted mass turns red, gives 

 a sublimate of benzoic acid, and develops an odor resembling 

 that of the oil of bitter almonds (benzonitrile ; C 6 H 5 CN, and 

 prussic acid, HCN). 



The red color is due to the decomposition of the glycocoll. 

 After the tube is cold, cut it off close below the sublimate and 

 place the upper part of the tube in a weak solution of sodium 

 carbonate in a test- tube. To .the solution resulting add a 

 little hydrochloric acid: precipitation of benzoic acid. 

 Examine under the microscope. 



3. Evaporate a small quantity of the crystals of hippuric 

 acid with some drops of fuming nitric acid, mix the residue 

 with some sand, put it into a tube and heat strongly: odor 

 of the oil of bitter almonds due to the formation of nitroben- 

 zene, C 6 H 5 N0 2 (Liicke's reaction). Benzoic acid and many 

 other acids of the aromatic series also give this reaction. 



VIII. PHENOL, C 6 H 5 OH, CRESOL, C 7 H 7 OH. 



PHENYL SULPHURIC ACID, CRESYL SULPHURIC ACID. 



(a) PHENOL. 



Radiating crystalline mass (if previously melted) or loose 

 crystals, forming an oily fluid with one-tenth its volume of 

 water. Melting-point 42; readily soluble in ether, in alco- 

 hol, and in fifteen parts of water. 



Reactions of Phenol. 



Use a 2 per cent, and a 0.2 per cent, solution of phenol 

 and make parallel tests. The conduct given in the following 

 experiments is for the 2 per cent, solution: 



1. Addition of ferric chloride solution: deep blue (ame- 

 thyst-blue) color. Strong acids discharge the color. Many 

 phenol derivatives, e.g., salicylic acid, give a similar reaction 

 with ferric chloride. 



