OF THE SYSTEM NAPHTHALENE-PHENOL. 



13 



accurate to 0.04°. The solution was stirred mechanically by 

 means of a thin glass rod, whose lower end was bent to form a 

 loop. The whole arrangement is shown in the annexed diagram* 

 The effect of supercooling, which is quite insignificant in 

 ordinary cryoscopic determinations, 

 is very considerable when the solu- 

 tion is concentrated. In order to 

 apply the correction for this effect, 

 a knowledge of the heat capacity of 

 the solution is necessary. This was 

 measured by the electrical method, 

 the current being passed through a 

 manganin wire of known resistance 

 immersed in the sokition. The dura- 

 tion of the current kisted about 200 

 seconds, and the rise of temperature 

 amounted to 2-3 degrees. The 



quantity of electricity was measured 



by means of a copper-voltameter. The determination was made at 

 a temperature slightly above the fusion point. It was not very 

 accurate, single measurements differing by 59^ in extreme cases. 

 Five or six determinations were, therefore, made for each solu- 

 tion and the mean was taken. For 20.16 gramme of naphthalene 

 and G grammes of phenol the heat capacity could be expressed 

 with sufficient approximation by the equation : 



H= 10.77 + 0.592 C. 



In this expression the lieat capacity of that part of the tube 

 which was in contact with the solution was included. The 

 equation is by no means exact, but it sufficed for the purpose of 



