Part XII. 

 GENERAL SUMMARY OF THE RESULTS. 



It seems desirable at the close of this extended series of papers to sum- 

 marize the more important results which have been attained, both in 

 order to make them more readily available to readers who may not be 

 interested in the details of the experiments, and in order to show more 

 clearly, by bringing together all the more significant results, the general 

 conclusions which can be drawn from them. 



In order to carry out these investigations a new form of conductance 

 vessel capable of withstanding high pressures and not liable to con- 

 taminate dilute aqueous solutions even at high temperatures had to be 

 constructed at the start. The vessel or "bomb" which was developed 

 as a result of several years' experimenting and which has been used 

 successfully with only minor modifications for all the measurements above 

 presented will be readily understood in its essential features by reference 

 to figure 1 on page 10, and from the following brief description : 



It consists of a cylindrical vessel A of about 125 c.cm. capacity 

 provided with a cover B which is held in place by means of a large 

 nut C, all these parts being made of steel. The bomb is lined through- 

 out with sheet platinum. The cover is made tight by a small packing- 

 ring of pure gold wire which fits into a small V-shaped groove. The 

 body of the bomb serves as one electrode. The other electrode is brought 

 in through the bottom of the bomb, being insulated inside by a piece of 

 quartz and outside by mica layers M. The quartz-piece Q is in the 

 form of a cylindrical cup about 2 cm. in external diameter and 2.7 cm. 

 in height, the bottom of it being covered on the inside by the circular 

 platinum-covered top of the electrode, which was usually well coated with 

 platinum black. In the cover is a narrow cylindrical chamber provided 

 with an auxiliary insulated electrode T 2 , which serves to show the 

 height of the liquid in the chamber and indirectly the volume of the liquid 

 in the bomb. The cover also contains a small platinum tube 7\ through 

 which the air may be exhausted from the bomb. 



In most of the experiments made with the more dilute solutions, the 

 bomb was modified, so as to reduce contamination, by removing the cup 

 and flat electrode within it, and replacing these by a cylindrical platinum- 

 iridium electrode usually about 10 mm. high and 7.2 mm. in diameter, 

 which was supported on a vertical quartz cylinder, through the center of 

 which the electrode rod passed downwards (see fig. 13, page 63). 



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