Mr. Davy’s Hypothesis of Electro-chemical Affinity. 25% 
condensation. They increased in a higher ratio as the 
sulphur approached its point of fusion; at a little above 
which these bodies combine with the evolution of hight and 
heat.- 
The electricity at 100° was barely sufficient to make 
the gold leaves diverge. How extremely low must lave 
been its intensity! for it is certain that the leaves of Ben- 
nett’s electrometer diverge with almost any change in the 
surrounding media. Thus, if powdered chaik be blown 
from the nosle of a bellows upon the brass cap, the leaves 
diverge; or it is only necessary to let the ehalk powder 
fall on the eap. Can it be supposed, although the elec- 
tricity increased in a ratio somewhat bivher towards the 
melting point of sulphur, which is 226°, that so low an in- 
tensity, as it still must be, could cause a combination at- 
tended by such a violent extrication of heat and light? 
I also have made some experiments on the contacts of 
different substances. A plate of insulated copper and a 
plate of glass were heated to about 130°. When separated, 
each caused a divergence of the gold leaves. - The electricity 
was always weak. Once, when the sun shone very strongly, 
the electrometer had acquired exquisite sensibility, and 
under these circumstances the divergence was somewhat 
considerable. I never afterwards succeeded so well. 
A plate of sulphur and a plate of glass, when heated and 
afterwards separated, caused a very sensible divergence of 
the gold leaves. When the glass on one side was coated 
with tin foil equal to the diameter of the sulphur, and 
heated as before, the leaves diverged nearly half an inch. 
These experiments exactly coincide with some made by 
Mr. Wilcke in a different manner. This philosopher found 
that, when sulphur was melted, and allowed to solidify 
in glass vessels, they both acquired a strong electricity ; 
but that the electricity was much stronger if ihe glass were 
coated. with metal. 
I repeated Mr. Wilcke’s experiment with some little va- 
riation. [ poured melted sulphur on a plane of glass, and 
cemented oman insulating handle. When solid, ts elec- 
tricity was so strong that it attracted large pith-balls as 
vigorously as if excited by strong friction. - The'i intensity 
of the glass was much lower. These experiments of melted 
sulphur do not differ from that of the heating of sulphur 
made by Mr. Davy, otherwise than that the former mode 
is more decisive; a complete contact is formed, and the 
heat is general and equal, and accordingly the results are 
less equivocal. 
Adpinus 
