ROYAL SOCIETY OF CANADA 



which is a value somewhat higher than that found for the mean of the 

 previous set. A mean of these two sets gives 



.91704 

 .91676 



.91690 

 as representing the most probable value. 



Heat of Fusion of Ice. 



With the density, the latent heat of fusion of ice has received a 

 large amount of attention. 



Black of Edinburgh, in 1762, was the first to draw attention to the 

 latent properties of the heat in melting ice. His first rough measure- 

 ment gave a value of 79.7 calories per gram. Strange to say this value is 

 closer to the real value than those obtained by many later investigators. 

 Lavoisier and Laplace, in 1780, determined the constant with their well 

 known double- walled ice calorimeter. They obtained 75 calories. In 

 1848 Eegnault obtained, by means of melting snow, the value 79.2 

 calories. Further experiments with small blocks of ice gave 79,06 

 calories. 



L. F. Guttmann has recalculated Regnault's results by correcting 

 for the erroneous value of the specific heat of ice used in the calculation 

 since the capacity for heat of ice was taken as equal to that of water. 

 He has also corrected Regnault's value for the variation of the specific 

 heat of water. This brings the latent heat of fusion of ice, as given by 

 Regnault, 79.25, up to 79.59 calories per gram. 



La Provostaye and Desains, in 1843, determined the constant and 

 obtained 79.25 and 79.01 as mean values. They were somewhat uncer- 

 tain of the amount of moisture adhering to their ice. 



Hess, in 1848, avoided this uncertainty by using ice cooled several 

 degrees below zero. He obtained 80.3 calories as a mean of his experi- 

 ments. Person, in 1850, carried out some experiments by a similar me- 

 thod and obtained a value of 80.0 calories. Both Hess and Person re- 

 quired a knowledge of the specific heat of ice cooled below zero. 



In 1870 Bunsen devised his well known ice calorimeter and deter- 

 mined the latent heat of fusion by adding known quantities of warm 

 water. The value he obtained was 80.02 calories. 



What may be regarded as the best and most accurate determination 

 of the heat of fusion of ice was made by Prof. A. W. Smith, in 1903. 

 Ice was broken into small pieces and cooled several degrees below zero. 

 It was then transferred to a calorimeter containing light oil also cooled 

 below 0°. The calorimeter and contents were then warmed slowly by a 



