ELEMENTS OF CHEMISTRY. 145 



touch the Electricities are concerned in the operations of che- tIes are . con - 



• , ^ . i . . . j j cernec in the 



mical affinity ; and that sometimes they are suppressed, and operations of 



at other times made to act in an opposite sense. It was even affinity, 

 observed, before the discovery of the Electric pile, that the 

 Equilibrium of Electricity is sometimes disturbed by chemical 

 operations, and the knowledge acquired from the labours of 

 the last ten or twelve years, has shown us, that there is not a 

 single action of affinity, in which the electricities do not co- 

 operate. 



We do not know how this co-operation is made, and, for in a manner " 

 i ,'-,.,• . not known j 



the moment, we must be satisfied with conjectures upon it. 



What we with certainty know is, that two bodies which have but bodies 



affinity for each other, and which have been brought into having affi- 



, /-j • . • nity, shew the 



mutual contact, are found upon separation to be in opposite e | e ;! tr j c sta te» 



states of electricity. That which has the greatest affinity for on separation, 



oxigen usually becomes positively electrified, and the other 



negatively. Bodies which have little affinity between them, that bochesbe ' 



° J . i , > , coming posi- 



or, which have nearly an equal affinity for oxigen, do not tive which hag 



sensibly derange the electric equilibrium by their mutual con- tbe stron g est 



. . affinity for 



tact. This is not only the case with combustible bodies, but oxigen. 



it also takes place with the oxides ; as for example, the oxalic 

 acid, dry and deprived of its water of crystallization, brought 

 into contact with quick lime, becomes, according to the ex- 

 periments of Davy, negatively electric, while the. lime be- E'evated tern- 

 comes positive. And since the electric state of these bodies P eratu '' e " n " 



r creases ihe af- 



is more marked, the higher the temperature, that is to say, as finities an.i the 



the chemical affinity becomes more active : and lastly, as at electncit y» and 



J ' J at the instant 



the moment of their union there is a production of heat, of union, heat 



which may vary from a very slight elevation of temperature to f n * ues P r °- 



i r i i cl . • . ,. babl y from an 



that of the most intense fire, we think we may conclude, electric di3- 



that at the moment of the chemical combination, there is a charge. 



discharge of the opposite electric state of the bodies, which 



here, as in the pile, produces the phenomenon of fire, at the 



instant when the electricities disappear. 



A derangement of the equilibrium of electricity appears A change in 

 therefore to precede, and as it were predispose, the action °f e qu Honum 

 the chemical affinity j though this phenomenon from physical precedes the 

 reasons cannot be always discovered by our instruments j as may a ~'" n °* * 

 happen, for instance, when one of the bodies is in the liquid 

 state. Davy found, in conformity with this, that sulphur, heated 



Vol. XXXIV.— No. 157. L upon 



