THE OXIDATION OF PHENOL. 137 



DEYIKG THE APPABATUS AND THE PHENOL. 



After the complete chain was closed by glass seals, with fife exception of the 

 two extremities and the stopcock g, the combustion tube was heated and a slow 

 current of hydrogen passed through for six hours. The portions of the ap- 

 paratus inclosed in the asbestos oven, shown in fig. 1 by the heavy lines, and 

 also the tubes F and G were heated to 140° for four hours after Avhieh the 

 hydrogen current was stopped and the apparatus allowed to stand for ten days. 



A pure sample of about 400 cubic centimeters of colorless phenol was em- 

 ployed as a starting material. It was distilled over a small piece of metallic 

 sodium " and the middle fraction collected in a receiver arranged to exclude the 

 light. After cooling, the flask was gently shaken and the crystals which im- 

 mediately formed represented only about one-half of the total mass, owing to 

 the sudden rise in temperature due to the crj'stallization of the supercooled 

 liquid. The melted portion was at once drained from the crystals. These were 

 again distilled and the middle fraction collected in the flask / through the side 

 tube. A small stick of metallic sodium was dropped in, the side tube sealed, 

 and a slow hydrogen current turned on. The purified sample was again dis- 

 tilled, the first fraction passing out through the tail of the stopcock g and the 

 middle fraction condensed in the flask S without stopping the distillation, by 

 quickly turning the stopcock. The flask / was then removed by sealing the outlet 

 tube below the stopcock g. 



The asbestos oven was heated to from 160° to 180° in the steady current of 

 hydrogen for two hours, the phenol partly vaporizing and collecting in the 

 receiver L. A small flame was then placed under the flask M and the phenol 

 boiled until about one-third had passed through the tubes J and K and col- 

 lected in E. The source of heat was removed from the oven and the phenol 

 condensed in the tubes J and K until they were about one-third filled. The 

 whole apparatus was cooled in the current of hydrogen and the distilling flask 

 sealed out of the chain by closing the tubes at 6 and c. The residue in the 

 distilling flask was colorless. 



In order to change the gas in the apparatus and avoid the phenol coming in 

 contact with oxygen which had not been heated (to eliminate the possibility of 

 the presence of ozone) the outlet a was opened and the hydrogen in the com- 

 bustion-furnace displaced by air. The combustion-furnace was again heated, 

 the oxitlet a sealed, and the hydrogen throughout the apparatus displaced by 

 air. The tube K was removed by careful fusion at the points d and e. 



The phenol in this tube (K) colored gradually when it was placed 

 in the direct sunlight until the oxygen was practically all in combina- 

 tion. On breaking one of the points ^^nder water^ the amount of oxygen 

 which had combined was shown by the amount of water sucked in. 

 Other tubes sealed in the same way were found to color more or less 

 rapidly depending largely upon the temperature. When cooled by con- 

 tact with broken ice, the coloration was only visible after several days' 

 exposure to a bright sun. When the temperature was nearly that of 

 the melting point of phenol, the color appeared in from fifteen minutes to 



" The sodium employed was in the form of sticks inclosed in small glass 

 tubing into which it has been introduced by melting in vacuo. Sections of the 

 tube of the desired length were broken and immediately dropped into the distill- 

 ing flask. By this means sodium of a comparatively pure quality, free from 

 moisture and hvdroxide, was obtained. 



