12 PHYSIOLOGICAL PHYSICS. [Chap. i. 



knob receive positive electricity, the inner coating will 

 be positively charged. Acting inductively through 

 the glass, it will decompose the neutral electricity of the 

 outer coat, repel the positive through the hand to the 

 ground, and attract the negative. The presence of 

 this negative electricity on the outer coat will allow 

 more positive to be given to the inner coat, which in 

 its turn will attract more negative to the outer, and 

 so on. Thus, in virtue of the inductive action of 

 the two coats on one another through the glass jar, 

 a much greater charge can be accumulated than on 

 any one coating beyond the influence of the other. 

 To discharge the jar at once it is only necessary to 

 connect the two coatings by the discharger, as shown 

 in the figure. To discharge the jar slowly, insulate it 

 it by placing it 011 a stool with glass legs, then touch 

 with the finger first the outer coating and then the 

 knob. At each touch a slight spark is seen. This 

 may be continued for some time before the charge is 

 dissipated. The jar was first made in the town of 

 Leyclen, its discovery being due to Cuneus, a pupil of 

 Muschenbroeck. It is also called Kleist's jar. Kleist 

 was a prebendary of Cammin, in Pomerariia, and is 

 said to have invented the jar independently of 

 Cuneus, and a year before him, viz. in 1745. A 

 shock may be given from a charged jar to several 

 people if they join hands and if the last one touches 

 the outer coating while the first one seizes the knob. 



An electric battery may be formed by placing 

 a number of Ley den jars in a box lined with tinfoil, 

 so that their outer coatings are in contact. The tin- 

 foil should be in metallic contact with fche metallic 

 handle of the box, from which a chain should pass to 

 the water-pipes of the house to give a good earth 

 connection. The knobs of the jars are all connected 

 by brass rods. The battery can then be charged from 

 the conductor of a frictional machine. 



