1890.] the Validity of Persons Absolute Zero. 19 



Monohydrate of Sulphuric Acid. The increase in the heat capacities, 

 both of the liquid and the solid, appear to be slightly greater near 

 the melting point than at more distant temperatures, but the differ- 

 ences are within the limits of the errors of the respective determina- 

 tions. They are : 



Increase. 

 Solid 0-00090 for 1 from -16 to - 7 (0 = f.p.) 



0-00050 -30 -J6 



Liquid . . 0-00045 + 1'5 + 18-3 



0-00031 +18-3,, +29-2 



Tetrahydrate of Calcium Nitrate. The determinations of the heat 

 capacity of the liquid show that there is a decrease instead of the 

 usual increase as the temperature rises. The values are : 



Decrease. 



0-00054 per 1 from -12'7 to + 8'6 (0 = f.p.) 

 0-00027 + 8-6 +28-8 



One of the determinations, it will be noticed, applied to tempera- 

 tures entirely below the freezing point. The heat of fusion was 

 determined by placing the bottle with the superfused liquid in the 

 calorimeter till the temperature of the latter had been attained, 

 raising the stopper of the bottle, and inserting a minute crystal of the 

 solid salt ; crystallisation then took place at the temperature of the 

 calorimeter, 25 below the normal freezing point, and its value at this 

 latter was calculated by adding to the observed value 25(C c) cal., 

 C c being 0'1481 at an average temperature of 12'5. This 

 method, where practicable, is more accurate than that usually 

 adopted. In the case of the solid salt the rate of increase of the heat 

 capacity is rather greater near the melting point, but the difference is 

 scarcely greater than the experimental error, and would not affect the 

 results to any appreciable extent. 



Naphthalene. The determinations with the liquid applied to one 

 interval of temperature only. The probable error is calculated from 

 the variation of the mean values deduced from the determinations 

 marked A, B, and C, these mean values being the result of com- 

 bining each of the determinations with those marked , /3, and 7. In 

 the case of the solid the determinations extended over two intervals 

 of temperature, the probable error in the value at being calculated 

 from the difference between the various duplicates. This substance 

 was less fully examined than the others, owing to its having already 

 been investigated by Alluard. 



Benzene. In the case of the liquid, the increase at the higher tem- 

 perature is rather greater than at the lower one. The values are : 



C 2 



