118 



DRS. L. MOND, W. RAMSAY, AND J. SHIELDS, ON THE 



Before being used the manometer was exhausted and found to give readings 

 practically identical with those of the barometer at the time. 



A quantity of palladium black was introduced into the experimental tube, the 

 capacity of which was determined. It was then fully charged with hydrogen and 

 exhausted as completely as possible at 100 C. before being placed in the calorimeter, 

 when it was sealed on to the burette, furnishing pure hydrogen, the pump, and the 

 manometer. 



After the experimental tube had remained several days in the calorimeter it was 

 found, by making connection with the manometer, that the internal pressure was 

 practically zero. The reduced readings of the barometer and manometer were 

 757'5 millims. and 7577 millims. respectively. It was estimated that the quantity 

 of palladium black in the calorimeter was now in a position to occlude over 110 cub. 

 centims. of hydrogen, which was admitted in four separate fractions. 



In estimating the amount of hydrogen actually occluded in each case, account was 

 taken of the unabsorbed hydrogen existing in the experimental tube before and after 

 the admission of the gas from the burette. The quantity of unabsorbed hydrogen 

 was ascertained from the known capacity of the apparatus (6'30 cub. centims.), its 

 temperature, viz., C., and the pressure indicated by the manometer. 



The deflection of the mercury meniscus in the capillary tube of the calorimeter was 

 corrected, when necessary, for the slight errors due to the fact that the bore of the 

 tube was not quite uniform. The results are given below in tabular form. 



HEAT of Occlusion of Hydrogen by Palladium Black. 



Altogether 111'61 cub. centims., or 803 volumes, of hydrogen were occluded in 

 addition to that which was already present in the palladium, and which could not be 

 removed in vacua at 100. From previous experiments (see table, p. Ill) this 

 probably amounted to a little over 50 volumes. 



