318 
Proceedings of Royal Society of Edinburgh . [sess. 
positive. To test this the heated charcoal was kept away from the 
funnel till all flame had disappeared. Then the vessel was put in 
position, and the deflections obtained in two experiments were — 
51 scale divisions positive in 10 minutes. 
lt)0 ,, ,, j> )j jj 
§ 7. Next an experiment was made with the burning charcoal 
put in position while a flame was visible. The flame remained 
visjble for 7 minutes, and in that time a negative electrification of 
34 divisions was obtained. Then the deflection came hack to the 
metallic zero in 1 .minute, and in 10 minutes more a positive 
electrification of 87 divisions (0*78 volts) was obtained. 
§ 8. Glowing coals taken from the fire and put at once in the 
vessel in position, repeatedly gave negative electrification ; but 
when they were kept away from the funnel till all flame had dis- 
appeared, the electrification obtained was slightly positive. Glow- 
ing coals remained glowing a very short time after all flame ceased, 
and the smallness of the observed effect is probably due to this 
cause. 
§ 9. A few experiments have also been tried to find to what 
positive potential the flame must be raised so as to overcome the 
negative electrification it gives to the air. Hitherto the only flame 
tried was a spirit flame. The positive electrode of a secondary cell 
was put into the flame of the lamp, and the negative electrode was 
joined to the iron funnel and to the case of the electrometer. The 
results obtained are not very regular, but we found that one storage 
cell was not sufficient to overpower the electrifying effects of the 
spirit flame. With one cell we got 45 divisions negative in 10 
minutes, instead of 109 divisions with metallic connection ; with 
two cells we got 10 divisions positive in 10 minutes; and with 
six cells we got 83 divisions positive in 4 minutes. 
§ 10. The filter, pump, and worm were now removed, and 
two plates — one of polished copper, and the other of polished 
zinc — were fixed 0’9 centimetre apart in a block of paraffin, as 
represented in fig. 2. The arrangement was such that either plate 
could be insulated, while the other was kept in metallic connection 
with the case of the electrometer. Observations were made to find 
the deflection from metallic zero with one plate insulated, and 
