of Zinc, Cadmium, and Mercury. 41 



Matthey succeeded in making the silica tubes for me. Tube A 

 (Si) was similar to the glass tube C, except that it was made 

 after the circular hole was measured. Tube B (Si) possessed 

 two ground caps, as already described, the apertures of 

 which were carefully measured. 



Two points on the curve (see fig. 2) for cadmium were 

 checked, using the two silica tubes, and for the higher point 



Fi 



g- 



Logp 

 - I 



M.P. ! 



M.P. 



— Vc- 



jj^b 



-^ 



*-5 



! M 



; V 



,,._ 



% 





!H 



F^v 



0-OCJSO iSO 170 ISO J90 200 210 220 230 240 J/ 



the_ smaller hole was used in connexion with tube Si B, 

 while for the lower one the 'larger hole cap was placed in 

 position. It is very satisfactory that the results of the two 

 sets of experiments agreed so well, as with tubes of different 

 kinds, any uncertainty in the correction for length and 

 standardization of the tube must have shown itself. The 

 two higher points obtained are shown at A on the curve, and 

 the lower ones at B. 



The experiments which have so far been carried out 

 show that the method is capable of general application, 

 and it is hoped that it may be possible to continue the 

 experiments for other metals. At very low pressures it 

 appears that the metal does not condense satisfactorily, and 

 results are not as accurate as was hoped for. The reason 

 may either be clue to collision with traces of residual gas, or 

 to repeated reflexion without condensation from the walls of 

 the tube. It has been noticed that metal condenses and 

 grows in a patch or streak, as if when it strikes the clean 



