134 GIBBS. 



localitj' are liardl}- comparable with those in which I have worked in the 

 Tropics. 



Richardson ' says: "Dr. Kolm also tells me that a degree of darkenin;» in 

 phenol, such as was obtained by me after three days' e.xposure in Clifton, England, 

 could only be produced after many weeks under the conditions xinder which he 

 has exposed it in Liverpool," and Kohn himself remarks ° that in his own experi- 

 ments the exposures have been made more under the conditions under which the 

 usual reddening of phenol oecxirs, the samples being exposed in the south windows 

 of a well lighted room. 



I am led to believe that active oxygen in any of its forms will react 

 with pure, dry phenol and consequently produce the coloration. Kohn 

 and Fryer ^° think that the oxidation of phenol goes on in the absence 

 of light and they make the following statement: 



"In respect to the action of light a series of experiments showed that the 

 coloration is produced in the dark, although slowly, and therefore the light acts 

 as an accelerator of the change only — an action of which there are many other 

 instances, * * * " 



They made exposures of dry phenol in dry air to the light conditions 

 in their locality and found no coloration in seven months. I have, 

 incidental to other work, exposed dry phenol in dry, pure oxygen to the 

 diffused light of this laboratory for several weeks, and moist phenol to 

 moist, atmospheric air in the dark at room temperature for two months 

 without any appreciable coloration becoming visible. Nevertheless, it 

 can not be considered proved that there is no reaction between oxygen 

 and phenol in the dark. In fact it is probable, from considerations 

 which will be advanced later, that a slow reaction takes place. 



Hydrogen peroxide reacts readily and I will show, in the experimental 

 part of this paper, that dry ozone is very reactive, either with the pui'e, 

 dry crystals or with melted phenol. The intimate association of water 

 with the coloration, which Kohn and Fryer olDserved, is thus explained 

 not as a compound necessary to the reaction, but as one of the products 

 of the reactions : 



C„H,OI-I+0=CJI,(OH)„ 

 C„H,(0H)3+0=C,H,0,+H,0, or 

 CoH,OH+50=C„H,0„+H,0. 



There is no doubt, however, but that the rate of oxidation is more 

 rapid in the presence of moisture. 



Chapman, Chadwick, and Ramsbottom " found that the presence of moisture 

 in the reaction between carbon monoxide and oxygen in the presence of ultra- 



' Loc. cit., 415. 

 » Loc. cit., 41fi. 

 '»Loc. cit., 111. 

 "Jovni. Chem. Soc. London (19071,97,943. 



