THE OXIDATION OF PHENOL. 145 



the wave length 328 m/i. Photographs made with improved apparatus 

 show the Praunhofer line U which has the wave length 394.8 /x/i. Since 

 the limit of visual sensibility of the human eye is about 400 /^ju (Nutting *" 

 says 330 /t/t) the above statement of Thomson can not be considered as 

 being strictly accurate. 



It is evident that ultra-violet light will penetrate to the interior of 

 a glass vessel exposed to the sun's rays, the quality of the glass being 

 an important factor. Eegener*^ states that glass absorbs the ultra-violet 

 rays below the wave length 300 /x/*. Fisher and Braehmer ■'^ have ob- 

 served that the coloration of manganese glass is produced slowly in th& 

 sunlight, more rapidly in high altitudes than in the lowlands, and in 

 a few hours on exposure to the rays of the quartz-mercury lamp, and 

 further that this effect is due in the latter case neither to the cathode nor 

 Eontgen ray, but to the ultra-violet light.*^ 



From these considerations one would expect that, under the most 

 favorable conditions, the production of ozone in the atmosphere at sea 

 level would be at a minimum (in the absence of other catalysts than 

 sunlight), while if the atmosphere or oxygen were inclosed in a glass 

 vessel, possibly only traces or none whatever would be produced as a 

 result of the action of the sun's rays and that if an equilibrium between 

 ozone and molecular oxygen is established it will lie at the point where 

 the ozone concentration is extremely minute.'*^ 



While it is possible that ozone may be produced by radioactivity, since 

 radioactivity is present in the atmosphere and M. and Mme. Curie** have 

 found that radioactive barium produces ozone in the air and Eicharzy 

 and Sehenk*^ have shown that oxj^gen is ozonized with feebly radioactive 

 radium bromide, it does not seem probable that an equilibrium between 

 the two oxygen states will be seriously affected by this influence, or 

 that it requires serious consideration among the causes which produce 

 the oxidation of phenol. 



EXPEKIMENTAI,. 



Two soda-glass tubes, 60 centimeters long and 16 millimeters inside diameter, 

 the glass less than 1 millimeter in thickness, were thoroughly dried and sealed, 

 inclosing an atmosphere of pure, dry oxygen, free from ozone and gas ions and 

 placed in the direct sunlight. The moisture was removed from the tubes by 

 sealing them on to the drying chain (see fig. 1) previously described, at the 

 point 6 and the chain was closed to moisture by a phosphorus pentoxide tube 

 sealed on at the right extremity. All of that portion of the apparatus inclosed 

 between the phosphorus pentoxide tubes was heated to 110° for six hours in a 



" Bull. Bureau of Standards 1908, 5, 265. 



" hoc. cit. 



"Fisher, Ber. d. deutsehen chem. Ges. (1905), 38, 946. 



"Ewell (Electrochem. & Met. Ind. (1900), 7, 23) states that the equilibrium 

 between oxygen and ozone at ordinary temperatures is almost infinitesimal. 



"Compt. rend. Acad. Sci. (1899), 129, 823. 



*' Journ. Chem. Soc. London (1904), Abs. 2, 399; Sitzungsler. Akad. d. Wiss., 

 Berlin (1904), 13, 490. 



