52 
Mr. W. Brande's Lecture on some 
experimentally demonstrated the identity of common and 
Voltaic electricity. 
More recent investigations, and especially the admirable 
researches of Sir H. Davy,. have fully established the correct- 
ness of these views, and have shewn that the different action 
of the Voltaic pile and the electrical machine, depends chiefly 
upon the quantity of electricity in the former being great, 
while its intensity is inconsiderable, and vice versa. 
In the following Lecture I shall have the honour of present- 
ing the Royal Society with some new inquiries connected with 
these objects of research, and have much pleasure in ad- 
ducing facts which throw further light upon this interesting 
department of chemical science, and which harmonize with 
the opinions of the able philosophers alluded to. 
§. II. 
When the flame of a candle is placed between two surfaces 
in opposite electrical states, the negative surface becomes most 
heated : this circumstance was considered by Mr. Cuthbert- 
soN as indicating the passage of electric fluid from the positive 
to the negative surface.* 
Mr. Erman has shewn that certain substances are unipolar 
in regard to the electricity of the Voltaic pile ; that is, that 
they are only susceptible of transmitting one kind of electri- 
city. The insulated flames of wax, of oil, of spirit of wine, 
and of hydrogen gas, only conduct positive electricity ; dry 
soap, on the contrary, and the flame of phosphorus, under the 
same circumstances, only transmit negative electricity. 
♦ Practical Electricity. 
f Annales de Chimie, 1807, Tom. LXI. p. 113. 
