-1859] WRITINGS OF JOSEPH HENRY. 313 



matter, there are no indications of electrical action; and 

 when the attractions and repulsions are thus neutralized a 

 body is said to be in its natural condition. 



7th. The electrical equilibrium may be disturbed by fric- 

 tion, chemical action, change of temperature, &c., or in other 

 words (by these and other processes) the fluid may be accu- 

 mulated in one portion of space, and rendered deficient in 

 another, and in this case electrical action is exhibited. 



8th. The phenomena are of two classes, namely statical, 

 or those of attraction and repulsion, in which the electricity 

 is at rest, and dynamical, or those in which the redundant 

 electricity of one portion of space is precipitated into that of 

 another in which there is a deficiency. 



9th. "When the electrical equilibrium has been disturbed 

 and a body contains more than its share of electricity, it is 

 said to be positively charged ; and when it contains less, it 

 is said to be negatively charged or electrified. 



The fourth proposition of this theory was added by Caven- 

 dish, in England, and by Epinus, in Germany, and was 

 found to be necessary in order to render the several parts of 

 the theory (as given by Franklin) logically consistent with 

 each other. At first sight it appears to be contrary to the 

 general fact of the mutual attraction of all bodies, but it 

 must be observed that when gross matter exhibits attraction 

 it is in its normal condition, and that since the electrical 

 force is infinitely more intense than that of gravitation the 

 latter may be a residual phenomenon of the former. 



According to this theory, there are two kinds of matter in 

 the universe, — aetherial or electrical matter, and gross (or as 

 it is frequently called by way of distinction,) "ponderable" 

 matter. The two however may have the same essence, and 

 diff'er from each other only in the aggregation of the atoms 

 of the latter; or what we call gross matter may be (as sug- 

 gested by Newton,) but a segregation or kind of crystalliza- 

 tion of the setherial matter in definite masses. Each kind 

 of matter is in itself entirely inert, has no power of spon- 

 taneous change of place, and is equally subject to the laws of 

 force and motion. A mass of ordinary "ponderable" matter, 



