GORDON. — DISSOCIATION OF FUSED SALTS. 



61 



The jacket Z>, containing the vapor, is a thin-walled glass cylinder 

 about 5 cm. in diameter, joined below by means of a Wood's metal or 

 mercury joint, W, to a cast-iron cup, /, on which the heating flame plays. 

 This vapor bath arrangement is such as is in 

 common use for V. Meyer vapor density deter- 

 minations at moderately high temperatures, ex- 

 cept that in the present case the jacket tube 

 was shortened. Inside of this vapor jacket is 

 the large test tube C, extending about 25 cm. 

 below the top of the outside jacket. So much 

 of the upper opening of the cylinder D as tiie 

 tube C does not fill is closed with the asbestos 

 sheet Bi. This covering is of course not air 

 tight, but makes it possible for the vapor to 

 ascend near the top without any rapid escape 

 into the room. In the tube (7 is the cell to be 

 measured. It consists of the silver electrodes 

 JlJi, £!.,, in the tubes Ai, A.^^ which contain the 

 two differently concentrated solutions of silver 

 nitrate, and the connecting solution *S^. The 

 capillary ends of the tubes A^, Ao, were lowered 

 beneath the surface of the connecting licjuid 

 only long enough for the measurements to be 

 taken. In order to prevent air circulation, the 

 top of the tube C was covered with an asbestos 

 sheet having holes for the tubes A and the ther- 

 mometer T. 



The heat was sup[ilied by a three-tube Bunsen 

 burner, fed from a gas supply containing a good 

 pressure regulator. By reason of this regu- 

 lator, when the gas was once adjusted, no care 

 was required to keep the heiglit of the vapor 

 constant, except as the amount of boiling sub- 

 stance made slow escape into the room. The 

 top of the condensing vapor column could be jilainly seen, and was kept 

 constant about 18 cm. above the lower end of the tube C. With this 

 arrangement any difference in tempei-atnre between the upper and lower 

 jvart of the liquid S was unnoticeable. 



Temperature. — The cells were measured at two temperatures, that of 

 boiling diphenylamine, and of boiling chinoline. The former was taken 



One Fourth Natural Size. 



