Absolute Quantity of Electricity in Matter. 431 



without committing oneself beyond what present facts will 

 sustain ; and yet it is equally impossible, and perhaps would 

 be impolitic, not to reason upon the subject. Although we 

 know nothing of what an atom is, yet we cannot resist forming 

 some idea of a small particle, which represents it to the mind ; 

 and though we are in equal, if not greater, ignorance of elec- 

 tricity, so as to be unable to say whether it is a particular 

 matter or matters, or mere motion of ordinary matter, or 

 some third kind of power or agent, yet there is an immensity 

 of facts which justify us in believing that the atoms of matter 

 are in some way endowed or associated with electrical powers, 

 to which they owe their most striking qualities, and amongst 

 them their mutual chemical affinity. As soon as we perceive, 

 through the teaching of Dalton, that chemical powers are, 

 however varied the circumstances in which they are exerted, 

 definite for each body, we learn to estimate the relative de- 

 gree of force which resides in such bodies : and when upon 

 that knowledge comes the fact, that the electricity, which we 

 appear to be capable of loosening from its habitation for a 

 while, and conveying from place to place, whilst it retains its 

 chemical force, can be measured out, and, being so measured, 

 is found to be as definite in its action as any of those portions 

 which, remaining associated with the particles of matter, give 

 them their chemical relation-, we seem to have found the link 

 which connects the proportion of that we have evolved to the 

 proportion of that belonging to the particles in their natural 

 state. 



853. Now it is wonderful to observe how small a quantity 

 of a compound body is decomposed by a certain portion of 

 electricity. Let us, for instance, consider this and a few other 

 points in relation to water. One grain of water acidulated to 

 facilitate conduction, will require an electric current to be 

 continued for three minutes and three quarters of time to 

 effect its decomposition, which current must be powerful 

 enough to retain a platina wire T ^ of an inch in thickness*, 

 red hot, in the air, during the whole time; and if interrupted 

 anywhere by charcoal points, will produce a very brilliant and 

 constant star of light. If attention be paid to the instan- 

 taneous discharge of electricity of tension, as illustrated in 



* I have not stated the length of wire used, because I find by experi- 

 ment, as would be expected^ in theory, that it is indifferent. The same 

 quantity of electricity which, passed in a given time, can heat an inch of 

 platina wire of a certain diameter red hot, can also heat a hundred, a 

 thousand, or any length of the same wire to the same degree, provided the 

 cooling circumstances are the same for every part in both cases. This I 

 have proved by the volta-clectrometer. I found that whether half an inch 



