THE OXIDATION OF PHENOL. 135 



violet light increases the rate of the formation of carbon dioxide and that while 

 dry carbon dioxide is decomposed by the light, in the presence of moisture no 

 decomposition could be detected. They conclude that in a photo-chemical reaction, 

 the catalyst (moisture) exerts a marked influence in determining the mode of 

 distribution of the energy amongst the molecules of the reacting substances. 



EXPEEI3IENTAL. 



Crystals of purest phenol were placed in a bulb tube and heated in 

 an atmosphere of dr}' h3'drogen until about 75 per cent volatilized. After 

 cooling in the current of hj^drogen, this gas was replaced by dry, 

 atmospheric air which had been passed through a purifying chain. The 

 tube was then carefully sealed and placed in the sunlight, at a tem- 

 perature of about 30°. The crystals- colored slowly with liquefaction, 

 until the entire mass had changed into a liquid of a deep red color. 

 The coloration was first noticeable in two hours and liquefaction was 

 complete after about five days, depending upon the quantity of phenol 

 and oxygen present, the size of the tube, the quality of the glass, and 

 some other factors. The experiment and results described were dupli- 

 cated several times. 



This work was then -repeated with the utmost care and with an ap- 

 paratus especially designed to eliminate all known sources of error. It 

 • permitted the double distillation of phenol over sodium in an atmosphere 

 of dry, pure hydrogen and the condensation of any desired fraction in 

 two tubes which could be sealed out of the apparatus independently of 

 each other, the replacement of the hydrogen with purified, dry at- 

 mospheric air or oxygen, and the treatment of one or both of the tubes 

 with ozonized oxygen in the dark. During all of these operations there 

 was no possibility for the entrance of moisture, for all of that portion 

 of the apparatus between the extremities of the drying tubes at both ends 

 of the chain was composed of glass vessels sealed in a continuous chain. 



DESCRIPTION OF APPARATUS. (fIG. 1.) 



The gases employed, hydrogen, atmospheric air, and oxygen, were purified by 

 passing through concentrated sulphuric acid, two tubes of calcium chloride, one 

 tube of soda lime, a combustion tube filled with purified asbestos heated to 

 redness, and then into the chain of apparatus shown in fig. 1. Here the gases 

 successively passed through a saturated solution of caustic potash. A, con- 

 centrated sulphuric acid, B, three tubes of phosphorus pentoxide held in place 

 by plugs of glass wool, C, D, and E, an ozonizer of tlie Siemen's '- form, F, and 

 a tube of tightly packed glass wool, 0. The next portion of the apparatus con- 

 sists of an arrangement of tubes and distilling flasks, inclosed in an asbestos 

 oven, for the handling of the phenol, and the tube of phosphorus pentoxide M, 

 with its end dipping under mercury in the dish ?f to exclude moisture. All of 

 the apparatus from A to Ts! was connected by glass seals. 



^' Ann. d. Phys. (1857), 102, 120. 



