Part II. 



ORIGINAL APPARATUS AND METHOD. CONDUCTIVITY AND IONIZA- 

 TION OF SODIUM AND POTASSIUM CHLORIDES UP TO 306. 



I. THE CONDUCTIVITY VESSEL OR BOMB. 



A vertical section of the conductivity vessel used throughout these inves- 

 tigations is shown in half size in fig. 1. It is a cylindrical vessel A, with a 

 cover B, which is held in place by the large nut C. A, B, and C are made 

 of soft crucible steel. To prevent contamination, the bomb is lined 

 throughout with sheet platinum 0.41 mm. thick. The cover joint is made 

 tight by a little packing ring, made of pure gold wire, which fits into a 

 shallow V-shaped groove. As may be seen in the diagram, the platinum 

 lining, indicated by a heavy line, goes under this ring and a little distance 

 beyond it, the outer edge being fastened to the shell by eight small steel 

 screws, of which two are shown. The lower vessel has a capacity of 

 about 122 c.cm. 



The body of the bomb serves as one electrode, connection being made 

 with it by means of the large binding post on top of the nut C. The 

 second electrode is brought in through the bottom of the bomb and is 

 insulated from the latter by means of the mica washer M, the air space 

 S, and the quartz-crystal piece Q. The body of this electrode is of 

 steel, but its upper part is covered with sheet platinum. On the bottom 

 of the crystal piece is turned a single sharp V-shaped ridge, and this 

 rests on a flat gold washer which is inserted between the crystal and the 

 bottom of the bomb. Another gold washer is placed between the upper 

 part of the electrode and a second V-shaped ridge turned on the upper 

 face of the crystal. The nut N fitting on the lower, threaded end of the 

 electrode, draws the latter down, thus forcing the ridges of the crystal into 

 the soft gold and making the joints tight. Z is a brass washer which by 

 its greater expansion-coefficient makes up for the difference in the expan- 

 sion, upon heating, of the quartz-crystal and of that part of the steel 

 electrode which lies within. The second nut, on the lower end of the elec- 

 trode, serves to bolt on a small copper tag to which the wire L 2 is silver- 

 soldered. The quartz piece Q is extended in the form of a cup above the 

 electrode, so as to increase the resistance-capacity of the cell. 



In the cover B is a narrow cylindrical chamber provided with an 

 "auxiliary electrode," which is insulated in just the same way as the lower 

 electrode. The purpose of this small chamber with the auxiliary electrode 

 is twofold : first, it serves as a safety device, showing that the bomb has 



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