r 319 i 



XI. Heats of Dilution of Concentrated Solutions. 



By WM. S. TUCKER, A.RC.Sc., B.Sc. 

 Communicated by Prof. H. L. CALLENDAR, F.R.S. 



Received March 23, Read April 22, 1915. 



CONTENTS. 



Page 



(1) Review of previous work on heats of dilution 319 



(2) Description of apparatus employed for determinations of specific heat and heat of dilution 



of solutions .321 







(3) Detailed observations for hydrochloric acid solutions 324 



(4) Study of the results obtained 329 



(5) Heat of dilution of lithium chloride solutions 334 



(6) Heat of dilution of sodium hydroxide solutions 334 



(7) Heat of dilution of calcium chloride solutions 338 



(8) Variation of heat of dilution with temperature for hydrogen and lithium chlorides . . . 338 



(9) Examination of THOMSEN'S results 344 



(10) General conclusions ... 349 



(l) REVIEW OF PREVIOUS WORK ON HEATS OF DILUTION. 



HEATS of dilution have been exhaustively studied by Prof. JULIUS THOMSEX for a 

 very large number of aqueous solutions.* His method chiefly consisted in taking 

 some concentrated solution and diluting it considerably. The total amount of heat 

 generated or absorbed in this process was thus found and quoted against the final 

 concentration expressed in molecules of water to one molecule of solute. It is to be 

 noted that during the process of dilution most of the thermal change occurs in the 

 early stages, and that after the first ten molecules of water are added the total heat 

 generated or absorbed increases but slightly. 



The probable reason for this procedure is, that the experimenter finishes the 

 operation with a dilute solution, so that starting with various initial concentrations, 

 he may need only a few specific heats of certain dilute solutions. It must be 



* ' Thermochemische Untersuchungen,' Bd. III. 

 VOL. CCXV. A 533. 2 U [Published August 25, 1915. 



