RICHARDS AND LAMB. — SPECIFIC HEAT OF LIQUIDS. 677 



Specific Heat of Cupric Sulphate Solutions hetween 0° and 17°. 



extrapolating linearly the results of Marignac between 18° and 52° a 

 result of 0.949 instead of the value 0.943 may be obtained, but this 

 extrapolation is too uncertain to form a satisfactory basis of comparison. 



In the same way, allowing for the heat of dilution, the specific heat of 

 a solution AgNOg + I96.7H2O was found to be 0.9476. This has never 

 been determined before at any temperature. 



As has been said, the heat of dilution was found before calculating the 

 above results. The results were as follows : 



The rise of temperature on dilution of the cupric sulphate solution with 

 an equal volume of water was found, in two experiments at 17° with 

 the divided beaker-calorimeter, to be +0.008° and +0.010", or +0.009° 

 in average. This is then a warming effect. 



The rise of temperature on dilution of the argentic nitrate was found 

 in the same way, in three experiments to be at 16° — 0.007°, —0.005°, 

 and —0.006° ; or —0.006° in average. This is a cooling effect, which was 

 duly subtracted from the final temperature of mixing in the specific heat 

 experiments. 



In these determinations the purity of the salts is not of paramount 

 importance, for the specific heats of the impurities would differ but 

 slightly from that of the pure salt; nevertheless, pains was taken to se- 

 cure high purity. An accurate knowledge of the concentration of the 

 solution is of more importance, and the solutions were all carefully ana- 

 lyzed. Even this, however, docs not require the greatest refinement for 

 the specific heats of the solution are so nearly equal at this dilution to 

 that of water that they change but slightly with changing concentration. 



