246 Observations and Experiments concerning 
Tt would seem as if this one’ fact were sufficient to esta- 
blish a decided difference between chemical affinity and 
electro-chemical attraction ; since the former is absent, where 
the latter is present in an ermine degree. 
Pursuing this reasoning, we find that, at the other wire, 
hydrogen is evolved. Mr. Davy has shown that the least 
oxidable metals easily unite to oxygen when their opposite 
states are exalted. Such is the case with silver. Now 
since silver in its natural state has little attraction tooxygen, 
and since in its exalted state it easily unites, is it an unfair 
conclusion, that, if made strongly negative, it should unite 
also to hydrogen? for, as the cause “of combination is the 
same in both, we ought to obtain the compound of silver 
with hydrogen as well as that with oxygen. If there be 
any difference in the cireumstances, it is that silver has na- 
turally some attraction to oxygen, and none to hydrogen ; 
which would cause the combination witb the former to be 
somewhat more quickly formed than that with the latter. 
Having now shown instances of bodies in different states, 
not combining, I proceed’ to the next position, that ‘* bo- 
dies in similar states do combine.” » 
With a view of ascertaining by direet means- whether 
bodies in similar states of electricity do combine, J] made 
the following experiment. 
Two cylindrical vessels (Fig. 1, Plate V.) one of glass, 
the other of metal, are connected by a stop-cock in such 
a manner that the ‘dock; when open, allows all the fluid of 
one vessel to flow into the other. The vessels are insulated, 
and have each a wooden stopper, through which a conduc- 
tor forms acommunication between an electric machine 
and the fluid within. There are quadrant and pith-ball 
electrometers, the ends of which also plunge in the fluid. 
The use of the conductors is to throw in an electricity, which 
must in both be of the same kind, as it is furnished from 
the same source; but to prove it beyond doubt is the use 
of the pith-balls, and can readily be done with sealing- 
wax in the usual manner. ~ The yuadrant electrometers in- 
varies. When copper wires, which readily combine with oxygen and are: 
easily soluble in acids, are used to transmit the electricity, the positive wire 
attracts the oxygen and acid, and repels the hydrogenand alkali But when 
platina wires are employed, which have but a very slight aflinity for oxygen,. 
{are not electric attraction and affinity the same ?] the phenomenon is very 
different. Oxygen and acid, as before, are attracted by the pasitive pole ;. 
but as they are incapable of uniting to the platina, {why ?] they instantly re- 
ceive by contact its electric state, and exercise a repulsive power towards it : 
the same effect takes place with the hydrogen and alkali at the negative pole.” 
This philosopher seems to have overlooked 4 position manifestly in con- 
tradiction te the hypothesis which he intends to support. 
dicate 
