Miscellanies. 19t 



ed with resin. When this was placed in a copper case, and plunged 

 in acidulated water, no magnetic effect was produced. The exte- 

 rior perimeter was then uncovered, and a magnetic force of 5.16 

 was acquired. The interior and exterior perimeters were then ex- 

 posed, and the force became 10.83. When the whole surface was 

 uncovered the force was 16.16. 



With a larger frame the exterior perimeter gave 8, the two peri- 

 meters 13.60, the whole frame 21.40. 



Having demonstrated this remarkable relation between the con- 

 tour and the surface of the zinc portion of the battery, the author 

 was urged by an earnest desire to ascertain whether the same kind of 

 relation took place in the copper portion. 



A plate of zinc of 14i square inches of surface was placed within 

 a double plate of copper, so that the latter covered the two surfaces 

 of the zinc without touching them. This element, put into a glass 

 vessel of acidulated water, gave a force of 28.20 ; 10| sq. in. of the 

 zinc were then removed, leaving a frame of 3i sq. in. ; the force 

 was 26.50. The copper was then cut in like manner, so as to leave 

 the zinc frame only covered with copper ; the force was 25.00. 



A similar element, with a zinc plate of 9 sq. in., covered with a 

 double plate of copper, gave 21.30. The zinc reduced to a frame of 

 3 lines in breadth, covered with a frame of copper of equal dimen- 

 sions, produced a force of 29.30. 



Another simple element of 4 sq. in. of zinc, with an equal plate of 

 copper, gave 18.25. The plate of copper was cut into a frame so 

 as to cover the two surfaces of the zinc, and the force rose to 21.87. 



Thus assured by direct experiments that the law of perimeters held 

 good in both the metals, the author constructed electromotors which 

 not only developed magnetic but calorific effects superior to those of 

 larger surface, but more circumscribed in the contour. But he also 

 ascertained that the magnetic action does not follow the same pro- 

 gression as the calorific. The former increases or diminishes in pro- 

 portion to the metallic perimeters, and the latter varies with the sur- 

 face of the metals agreeably to some unknown law. 



With respect to the electric action elicited by an electromotor of 

 zinc and copper, it is manifest only when the circuit is interrupted. 

 But if the circuit be completed by the spiral of the temporary mag- 

 net, this action becomes manifest, because the magnetic action then 

 developes its greatest force, but the electric action is not manifest. 

 When the circuit is broken, the magnetic action is disguised, and the 



