16 



Conductivity of Aqueous Solutions. Part II. 



haps 20 cm. long and 5 cm. square, and whittle one end down so that it 

 will slip easily into the bomb. Then take a piece of cotton cloth moistened 

 with alcohol to remove any grease, wrap it over the small end of the 

 stick, and then with a hammer drive the latter tightly into the bomb. Now 

 holding the bomb in the vise, grasp the projecting end of the stick firmly 

 in the hands or in a wooden clamp and twist out the lining. This method 

 never fails, provided the steel shell was ground reasonably smooth at the 

 start. 



A hole is drilled in the lining at the bottom so as to correspond with the 

 hole in the steel shell. It is then best to close this hole temporarily with 

 the steel piece shown in fig. 3, using a lead washer under the V-shaped 

 ridge for packing. Then, in order to bring the lining into perfect contact 

 with the shell and at the same time to test it for possible faults, the lower 

 part of the bomb is connected by means of the auxiliary cover shown 



in figure 4 with 



X A 



L___ 





^ 



X 



B 



a Cailletet pump 

 or its equivalent 

 a water reservoir 

 being interposed 

 between the pump 

 and the bomb so 

 as to force water 

 instead of oil into 

 the bomb. For this 

 Fi - 3. Fig. 4. Fig. 5. testing of the lining 



a pressure of 300 

 atmospheres has been used, the steel shell having previously been similarly 

 tested up to 600 atmospheres pressure. The lining must be fitted as closely 

 as possible before the hydraulic pressure is applied, since otherwise this 

 will always result in tearing the lining. Even after expanding the lining 

 with hydraulic pressure, there is no trouble in removing it, in case a leak 

 develops, by the method given above. 



The next step is to fasten the edge of the flange to the shell. If this is 

 not done, when substances like benzophenone, solid at ordinary tempera- 

 ture, are employed for heating the bomb, they will be drawn under the 

 flange and into the groove in the shell, where they will solidify ; upon heat- 

 ing the bomb the next time, the solid melts and escapes, thus relieving the 

 pressure on the packing-ring and allowing the bomb to leak ; moreover, if 

 the edge is not fastened down, there is danger of bending it when the 

 bomb is opened and handled. To secure the flange eight small steel screws 

 are used. The steel shell has to be recessed at this place, as shown in 

 fig. 1 ; otherwise the screw heads would interfere with the cover. 



