OF THE SYSTEM NAPHTHALENE-PHENOL. 15 



Phenol is very difficult to obtain pure. Tlie loose crystals 

 got from Kahlbaum were dried and distilled, and the middle 

 portion of the distillate was collected separately. Its melting 

 point was 40.58°C. The greatest danger lay in the hygroscopic 

 nature of the substance. It was kept melted in a long necked, 

 round bottomed flask, and transferred to the fusion tube by means 

 of a pipette which carried a cork fitting closely to the mouth 

 of the flask. The flask was weighed with the pipette and the 

 content, and in this way the quantity of phenol added to the 

 solution w^as determined. But as the weather was very wet during 

 the whole period of the experiment, hygroscopic moisture could 

 not be excluded completely. This was particularly troublesome, 

 because one series of measurements extended over more than ten 

 hours. For errors from these sources it is impossible to apply 

 corrections. The fact that the eutectic point arrived at by 

 following up the fusion curve of naphthalene was more than a 

 degree below that found by following up the fusion curve of 

 phenol, is to be explained by the greater amount of moisture 

 absorbed in the former case, because the time which had elapsed 

 from the beginniiig of the experiment was very much longer, 

 and the manipulations were repeated much oftener. 



Ö. Numerical Data. 



The following table gives the experimental data on the fusion 

 curve of naphthalene obtained in one series of determinations. 



The first column gives the number of observations. In the 

 second column are tlie fusion points in absolute temperature, the 

 absolute zero being set at — 273.00°C. In the third column, 

 the degree of supercooling is given. In the fourth, the quantities 



