148 



Dr. J. Monckman. The Specific 



Table showing the action of Heated Sulphur upon Platinum 

 Electrodes. 



Deflection produced 

 After an by a constant 



exposure of — electromotive force. 



60 minutes 22 scale divisions. 



90 29 



120 

 140 

 200 

 260 

 275 



32 

 33 

 40 

 43 

 44 



Lastly, the same graphite rods were used as in the previous experi- 

 ments. These electrodes had been repeatedly exposed to high 

 temperatures, and also boiled many times in sulphur. After being 

 kept at temperatures varying probably not more than from 400° C. to 

 440° 0. during five hours, the conducting power of the liquid was 

 practically the same as at first. 



Thus, at 12.50 p.m. (boiling) the deflection was 290 scale divisions. 



The flame was then slightly reduced, and at — 



1.20 p.m 260 scale divisions. 



3.30 p.m 150 



The flame was then raised again, and at — 



4.30 p.m 220 scale divisions. 



5.30 p.m. (boiling) 280 

 5.50 p.m. „ 280 



New graphite electrodes were next tried, and found to discolour the 

 sulphur considerably ; but the resistance was increased. In all cases 

 the current passed. The objection to using the same electrodes, even 

 after using great care in cleaning them in the different liquids, and in 

 that way contaminating them, and the impossibility of getting new 

 ones that would do without previous boiling in sulphur, caused me 

 to abandon their use altogether, and to depend upon a short exposure 

 of platinum instead. The conclusion, determined by the work 

 described, was that using combustion-tubing for boiling and well- 

 cooked graphite electrodes, the change produced by chemical action is 

 practically nothing, even after boiling several hours, if the containing 

 vessel be protected from the direct flame, and that in the case of 

 platinum electrodes, it tne observations are taken immediately they 

 are inserted into the liquid, the action is slow enough to allow 

 measurements to be taken without fear of error. 



