electrical and chemical changes. 
4i 5 
VIII. General observations and practical applications. 
To explain the manner in which different chemical agents 
in combination, and in a perfectly neutral state, instantly start 
into an active existence, when exposed to the two electrical 
poles, it is necessary to assume principles, and take views of 
corpuscular action of a perfectly novel kind ; and as the 
chief agents are invisible, and probably imponderable, no 
direct demonstrative evidence can be brought forward on the 
subject ; and different hypotheses may in consequence be 
applied to it. In assuming the idea of two ethereal, subtile, 
elastic fluids, attractive of the particles of each other, and 
repulsive as to their own particles, capable of combining in 
different proportions with bodies, and according to their pro- 
portions giving them their specific qualities and rendering 
them equivalent masses, it would be natural to refer the action 
of the poles to the repulsions of the substances combined 
with excess of one fluid, and the attractions of these united 
to the excess of the other fluid ; and a history of the pheno- 
mena, not unsatisfactory to the reason, might in this way be 
made out ; but as it is possible likewise to take an entirely 
different view of the subject, on the idea of the dependence 
of the results upon the primary attractive powers of the parts 
of the combination on a single subtile fluid, I shall not enter 
into any discussion upon this obscure part of theory, but I 
shall endeavour to clear the way for elucidations of it by 
stating some experimental results. 
