334 



MR. W. S. TUCKER ON HEATS OF 



(5) LITHIUM CHLORIDE. (Molecular weight 42'5.) 



The solutions of lithium chloride were treated in precisely the same way as those of 

 hydrogen chloride. The solutions when concentrated, possessed a much greater 

 viscosity and greater care had to be taken in stirring. Also the solutions were very 

 hygroscopic and the experiments were performed, as far as possible, in an air-tight 

 vessel. 



The following tables (Tables V. and VI.) summarise the observations. As the same 

 mixing vessel was used and the same quantities of solution, the same water equivalents 

 were employed. In the specific heat determinations the current and voltage employed 

 are the mean of sixteen observations for each solution. The specific heats were 

 obtained for nearly the same range of temperature as that employed for the heat of 

 dilution determinations, hence no temperature correction for specific heat need be 

 applied. Seven specific heats were found and 300 c.c. of each solution were taken. 



The curve connecting heat of dilution and concentration shows a more gradual 

 increase of the former with increase of the latter. The same peculiar property, 

 however, is shown for concentrations exceeding LiCl . 6H 2 O above this value to 

 concentration LiCl . 3H 2 0, the truest representation for this portion is a straight line 

 which cuts the concentration curve at LiCl . 8H a O. (Diagram II.) 



For this range the equation may be written 



Jg = 6927 



dN 



-0125J- 



A few experiments have been performed by DUNNINGTON and HOGGARD with 

 lithium chloride ('American Chemical Journal,' vol. 22, p. 210, 1899). Their method 

 was only approximate, as they did not attempt high accuracy. The following few 

 results show good agreement with those obtained above : 



LEMOINE* has determined heats of dilution for some concentrations of lithium 

 chloride, but his results are not expressed to give a high degree of accuracy sufficient 

 to compare with the above results. 



(6) SODIUM HYDROXIDE. (Molecular weight 40.) 



With solutions of sodium hydroxide the same processes were employed. It was 

 found more convenient to take 250 c.c. of the solutions for the specific heat 

 determinations. 



'Comptes Rendus,' vol. 125, 1897, p. 603. 



