1807. ^ET. 29.] PEOFESSOR DAVY. 343 



On October 6 he began * a new series of experiments 

 on polarity.' 



From the account he gives of one experiment, 

 it appears that he exposed different substances on a 

 glass plate to the action of the platinum wires from 

 a galvanic battery of 100 plates of 6 inches. 



He tried the following substances : oxalic acid, dry ; 

 succinic acid ; oxalic acid ; soap ; alcohol ; water ; 

 carbonate of ammonia ; nitrate of potash. He wrote, 

 ' Pure potash, as dry as it can be made, discharges 

 the negative in a remarkable degree and insulates the 

 positive.' 



6 Remarkable, Phenomena with Potash. It soon ' 

 Here the laboratory note ends, but his paper in the 

 ' Philosophical Transactions ' says ' fused, became a 

 conductor, and gave brilliant light with the appear- 

 ance of flame at the negative wire. When it was 

 slightly moistened, to make it a better conductor, the 

 potash began to fuse at both its points of electrisation; 

 there was a violent effusion at its upper or positive 

 surface, while at the lower or negative surface there 

 was no liberation of an elastic fluid, but a formation of 

 small granules resembling quicksilver, which occasion- 

 ally burst with explosion.' 



He then tried carbonate of ammonia, sulphuric acid 

 and water, soap, and the flame of a candle. 



The following day carbonate of ammonia and 

 oxalic acid were tried, sulphuric acid, water, and 

 alcohol. 



From the 7th to the 16th no experiments were 

 entered in the Laboratory Book ; but to the substance 



