190 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Heat Capacity Data (in terms of water equivalent). 

 Water in calorimeter = 450.19 grams 



Calorimeter and fittings = 12.24 " 



21.37gms.NaOH(sp.ht.= 0.8345)= 17.83 " 

 1 14 . 80 gms. H2SO4 (sp. ht. = . 95) = 109 . 06 " 



Total Heat Capacity =589.32 " 



Total evolution of heat (Q) 589 . 32 X 4 . 224° 2489 . 3 calories 

 Heat per 100 grams of acid (^loo) 2168.4 



Heat per i Mol Acid (U) 16949 



For the sake of convenience, the heat evolved per gram ec^uivalent 

 of sulphuric acid is called U. 



All the other experiments upon water were essentially similar in 

 character to this. They were, however, carried out at several different 

 temperatures in order that the temperature coefficient of the reaction 

 might be measured under precisely the conditions of the experiment, 

 because the heat of neutralization varies decidedly with the tempera- 

 ture. The final temperature of the reaction is taken as the tempera- 

 ture corresponding to isothermal evolution of heat, because the heat 

 capacities of the factors were used in computing the total heat capa- 

 city. -"^^ In this and in all the subsequent computations the specific 

 heat of water over the same range is taken as the unit. As the matter 

 is entirely one of comparison between similar experiments, this is 

 entirely permissible and reduces all to the same basis. After these 

 introductory remarks the two series of experiments with water alone 

 in the calorimeter at about 20.7° and 19.8° C. are given below in 

 order that the range of accuracy of the experiments may be seen. 

 In this table, as before, Qm stands for the heat evolved during the 

 neutralization of 100.0 grams of dilute acid, and U signifies this same 

 result calculated in terms of the gram equivalent of sulphuric acid. 



Inspection of the results shows on the whole a very satisfactory 

 constancy. The three experiments of Series I deviate from the 

 mean by less than one-fortieth of one percent, all having been taken 

 at about the same temperature. The five experiments of the next 

 series are less satisfactory, Ijut the last three are completely con- 

 cordant with one another and with the mean. 



From the two averages 16,946 and 16,993, taken at 20.72° and 

 19.77° respectively, it is easy to compute that the temperature co- 



10 Richards. Journ. Am. Chem. Soc, 25, 209 (1903). 



