362 GIBBS. 



Probably a oorallin or trop:i?oliii compound formed by the action of ammonia 

 and ozone of the air prduces the color. 



A. Kremel ' believes that the red color is produced bj' a large number of metals 

 and metallic oxides, particularly copper, and then lead, silver, and zinc. Tin has 

 no action. He says that these metals enter into combinations, the result being 

 that these compounds dissolve in phenol with a red color. This compound can not 

 be rosolic acid for the reason that it dissolves in concentrated sulphuric acid with 

 a blue color, whereas rosolic acid does so with a yellow color. E. M.ylius ^ believes 

 that the glass vessels exercise an influence by giving up alkali when they are easily 

 acted upon by the phenol. 



E. Fabiiii ° states that the red color is due to the action of hydrogen peroxide 

 in the presence of metallic salts and ammonia. He ascribes the formation of the 

 color to the production of ammonium phenate which is converted into a phenate 

 of the metal present, iron or copper, and which is in turn acted upon by 

 hydrogen peroxide, yielding the red coloring substance which he calls phenery- 

 threne. This compound is soluble in alcohol and phenol, coloring the latter red. 

 It dissolves in sulphuric acid with a blue color. 



A. Bidet '° states that phenol which is carefully purified will remain colorless 

 on exposure to air and light. W. Hanko ^' finds that the coloration is due princi- 

 pally to oxidation. The presence of thiophen, creosol or parakresol does not affect 

 the color. Metals such as copper, iron, and lead and their salts, as well as ammonia 

 and ammonium chloride, accelerate its formation. J. Boes ^ believes it to be 

 highly probable that an isophenol described by Brunner " is the cause of the red 

 coloration. Cirmaronon is not the cause. 



Kohn and Fryer " have found that the coloration requires the presence of 

 moisture, air, and light rays, or in the absence of light rays, hydrogen peroxide, 

 and that the presence of metallic impurities accelerates the color formation. They 

 conclude that the colored compound is an oxidation product of phenol and can be 

 formed in pure phenol under the proper conditions of light, moisture, and oxygen. 

 No coloration occurs when the phenol is protected bj' ruby glass. 



A. Richardson '^ has proved the presence of hydrogen peroxide in phenol which 

 has been exposed to the light and he concurs in the opinions of Kohn and Fryer. 

 The light waves at the blue end of the spectrum are the ones which produce the 

 effect and not those at the red. 



Kohn ^° repeats that the coloration will take place in pure phenol, when moisture 

 and oxygen are present, under the action of the more refrangible light rays. 

 A. Bach " says that while phenol reddens by the action of air, moisture and light 



'J. Soc. Chem. Ind. (188G), 5, 160. 

 ^Chem. Cmtrbl. (1887), 18, 251. 

 "J. Soc. Ghem. Ind. (1891), 10, 453. 



"•Bull. Soc. Chim. Paris (1891), III, 5, 13. Compt. rend. Acad. d. sc. Par. 

 (1889), 108, 521. 



"■Ber. d. chem. Oes. (1892), 25, 386, Eef. 



•"Ghem. CenirU. (1902), II, 73, 50. 



"./. pr. Ghem. (1902), 173, n. s. 65, 304. 



"J. Soc. Ghem. Ind. (1893), 12, 107. 



•'Ibid, 415. 



•'Ghem. A'etts (1893), 68, 103. 



"CTew. Gentrbl. (1894), II, 65, 318. 



