LXVII. Theory of the Electric Residue in the Ley den Jar. 



By R. KOHLRAUSCH. 

 [Continued from p. 320.] 



§6. 



TT is clear the question may arise, whether the cause of the 

 -^ residue does not reside in the uncoated part of the jar or 

 rim, inasmuch as a part of the electricity may move about be- 

 tween the glass and the varnish. 



It appears plausible, that if such a movement occuiTed, it 

 would do so gradually and in tolerable quantity, for the electri- 

 city pushed on to the rim on the insulated side would cause the 

 opposite electricity to follow it up the other side, and condensa- 

 tion might take place as well on the insulator as under the 

 coatings. At any rate the decision of this question does not 

 a2:)pear supei-fluous. 



If the rim of the jar actually influences the residue, then this 

 influence ought to be more considerable, in proportion to the 

 total charge, not only when the rim is broader (for it might be 

 assumed that the movement was never very extensive), but parti- 

 cularly when the periphery of the coating is greater in compari- 

 son to its superficial area. Hence if, with an equal area of 

 coating, the rim be reduced to a minimum, the residue ought to 

 be reduced also. 



The neck of the bottle which was desci'ibed in § 1, under b, 

 and to which the tables b, b', b" belong, had a circumference of 

 5*7 centims., and an interior surface of 11'4 square centims., 

 whilst the part of the interior surface of the same bottle which 

 was covered with mercury contained 275 square centims. 



The metallic coating of the Franklin's plate, which was de- 

 scribed under e in § 1, and to which the tables c, c', and c" 

 belong, formed a rectangle whose sides measured 15 and 25 

 centims., whose periphery therefore was 80 centims., and area 

 375 square centims., whilst the surface of the uncoated rim 

 amounted to 296 square centims. 



If now we compare the tables Z>" and c" of § 4, we shall find 

 that in 864 seconds, and with a primitive charge of 0*5559, the 

 Franklin's plate had concealed the residue 0-1060; whilst the 

 bottle b in 935 seconds, and with a primitive charge of 1'4968, 

 produced the residue 0*4522, which is equivalent to a residue of 

 about 0*4445 in 864 seconds, i. e. in the same time as the 

 Franklin's plate. Hence, notwithstanding the unequal propor- 

 tions of rim, the residue amounted to 0'297 of the original 

 charge in the bottle, and 0"190, in the Franklin's plate. The 

 proportion will be about the same if we compare these residues 



