498 Sir W. Ramsay and Dr. B. D. Steele on the 



through which water is made to circulate. The temperature 

 of the volume-tube A, from its top to where it enters the 

 mercury c, required to protect the rubber cork d from being 



Fig-- 1. 



attacked by the hot chlorobenzenC;, is that of the chloro- 

 benzene vapour, that of the portion standing in water is also 

 known, and that of the intermediate portion is determined by 

 means of a thermometer with a long bulb ^, of the same 

 length as the portion of tube of unknown temperature; the 

 temperature is thus integrated between the point c and 

 the surface of the water. The temperature is read on the 

 stem /. 



The volumes of the vapour are determined by adjusting 

 the surface of the mercury to a set of points 1 to 8, of blue 

 enamelled giass^ which should be ground on a whetstone 

 with oil in the manner recommended by Lord Rayleigh. To 

 determine once for all the volumes indicated by the different 

 points stopcocks were sealed to the end of the tube at a and 

 to the end of a, as shown in fig. 2. The tube was completely 

 exhausted with a Topler pump, and filled with warm mercury: 

 by attaching a Fleuss pump to the exit of the weighing-flask 

 F the mercury flowed out through the capillary end of the 



