292 

 therefore 



A. W. Witkowski on the 

 M 2 5 X 1 



a P)6 = (l + cip,t.t) 



e 



(2) 



§ 4. Description of Apparatus. — A general representation 

 of the apparatus I have used to obtain the values of the co- 

 efficient a. will be found in fig. 1. 



Fig. l. 



The vessels denoted above by s x and s 2 are two thick-walled 

 glass bulbs, melted on to capillary stems (T X and a 2 , the diameter 

 of bore of which is less than £ mm. On each of the capillary 

 tubes a mark m is drawn at a distance of 3-4 cm. from the 

 bulb, to limit the capacity s. The capacities of bulbs and 

 stems were measured repeatedly, before and during the 

 experiments, by mercury weighings. The capacities s x and 

 s 2 were nearly 2000 c.mm. (in some experiments at the lowest 

 temperatures, only 1000 c.mm.) ; the capacities of the capillary 

 stems (o - ! and <r 2 ) were not more than 8 to 10 c.mm. 



The upper end of each siem (<r l and cr 2 ) is connected with 

 a sort of distributing apparatus, provided with two screw- 

 valves, of which one is used to fill the bulb with gas, the other 



