1099 
In the system ethane-naphtalene I succeeded not only in finding the 
point p, but also g. 
The ethane was prepared by electrolyzing sodiumacetate. The 
anode gas was purified by bromine water and a strong solution of 
potassium hydroxide, dried over sodalime and condensed in a receiver 
by liquid air. Subsequently it was again dried over phosphorus 
pentoxide and separated from the more volatile part by fractionating 
by the use of liquid air. The disappearance of the discharge in a 
GrIsLER tube attached to the apparatus served as criterion of purity. 
I determined the critical point from three fractions of the so purified 
ethane. The following well agreeing values were found: 
Ist fraction) 31.8° | 48.23 atm. 
2nd fraction! 32.3° mean | 48.09 atm. ean 
| le) 
3rd fraction) 32.350 | 32-32° | 48.18 atm, | 48-13 atm. 
The further investigations were made with the second and third 
fraction. 
The naphtalene was purified by sublimation; the melting-point 
was 80.8°. . 
The apparatus represented in fig. 3 was used for the preparation 
of the mixtures. 
A is the storing-vessel with purified ethane. B is calibrated. In C 
ethane may be condensed by liquid air, whereas D is filled with 
cocoanut charcoal to absorb the last traces of air after the evacua- 
tion of the apparatus. The Cailletet tube / was connected with the 
rest of the apparatus by rubber tubing protected by mercury. A 
weighed quantity of naphtalene and an electromagnetic stirrer were 
placed beforehand in the Cailletet tube and fused on to the top by 
carefully heating. After exhausting the whole apparatus, the naphtalene 
being cooled by solid carbonic acid and alcohol, ethane of definite 
pressure, to be read on the manometer G, was pressed over 
into the Cailletet tube by the aid of air-free mercury contained 
in the vessel /’; in this way the required quantity of gas was 
mixed with the naphtalene. The tube was then placed in the pressure 
cylinder filled with pure mercury freed from air by boiling. The 
tube was heated and the pressure regulated in the same way as 
