234 INDUCTIVE AFFINITY. 



conductors are used. When a silk handkerchief or a piece 

 of resin is rubbed upon glass, both are found, after separation, 

 in a polar condition, and continue in it. The rubbing surface 

 of the glass is zinco-polar, and that of the resin or silk is 

 chloro-polar, and a molecular polarization is at the same time 

 established through the whole mass of both the glass and 

 resin, reaching to their opposite surfaces, which exhibit the 

 other polarity. The powers thus appearing on the two rubbing 

 surfaces, being manifestly different, were distinguished by the 

 names of the bodies on which they are developed, that upon 

 the glass as vitreous electricity (zincous affinity), and that upon 

 the resin as resinous electricity (chlorous affinity). 



In comparing the chemico- polarity excited by friction with 

 that of the voltaic circle, we observe that the former is of high 

 intensity but small in quantity, or affecting only a small number 

 of trains of molecules. If both the excited vitreous and 

 resinous surfaces have a conducting metal, such as a sheet of 

 tin-foil applied to them, and each sheet have a wire proceeding 

 from it, the wires and tin-foil are polarized similarly to the 

 glass and the resin which they cover, and a zincolyte placed 

 between the extremities of the wires, which are respectively 

 a zincoid and chloroid, is polarized also, and decomposed. But 

 the amount of decomposition, which is a true measure of the 

 quantity of induced particles, is extremely minute compared 

 with the amount of induction in the voltaic circle. Thus, Mr. 

 Faraday has calculated that the decomposition of one grain of 

 water by zinc in the active cell of the voltaic circle, produces as 

 great an amount of polarization and decomposition in the cell 

 of decomposition, as 950,000 charges of a large Leyden battery, 

 an enormous quantity of power, equal to a most destructive 

 thunder storm. The polarization from friction is therefore 

 singularly intense, although remarkably deficient in quantity, 

 or in the number of molecules affected. 



The kinds of matter susceptible of this intense polarization 

 are so many, and so various, such as glass, minerals, wood, 

 resins, sulphur, oils, air, &c., as to make it difficult to sup- 

 pose that the polar molecule is of the same chemical consti- 

 tution in all of them, as it is in the zincolytes of the voltaic 

 circle. Indeed it must be admitted that all matter whatever 

 may be forced into a polar condition, by a most intense in- 



