isa 



UNDULATORY FORCES. KLECTH1CITY. [L.'MIMODS EFFECTS, 



Wliea the battery is oluuged, it is to be discharged by 



means of the usual discharger; and the mechanical 

 effect will be such that portions of the gold leaf will be 

 driven into the glass, and the two plates shivered into 

 numerous small pieces. This experiment requires great 

 care, as the broken pieces are exceedingly sharp, and 

 fly to a considerable distance on all sides. It is advis- 

 able that a kind of screen be placed over them, to pre- 

 vent accident to the experimenter. The following 

 engraving illustrates the whole arrangement. 

 Tig. . 



We have frequently shivered into almost dust, by 

 means of the hydro-electric machine and twelve large 

 jars, pieces of glass a foot long and four inches wide. 

 For this and many other similar experiments, a con- 

 venient arrangement may be made, which in illustrated 

 in the following figure. 



Fig. 30. 



In the engraving, a b are two brass rods, which are 

 easily moved on universal joints, secured to two glass 

 pillars, e e ; d is a small table, on which the object to be 

 experimented on is to be placed ; e and / are two wires 

 for conducting the electricity from the battery. One of 

 tuese is to be attached to the outside of the battery, 

 and the other to the discharging rod, so that when the 

 battery is charged, the electricity may be thereby con- 

 veyed to the table of the apparatus. We shall suppose 

 that the student will supply himself with an arrange- 

 ment of this kind, which, in fact, ho can easily con- 

 struct, in a rough way, himself ; and which he will tind 

 a matter of great convenience. We shall in future call 

 it the "universal discharger." We may add, that a 

 similar arrangement will be required for many experi- 

 ments in voltaic electricity. In the engraving, we have 

 represented the ends of the discharger as terminating in 



two brass balls will, however, be occasionally 

 required in some of the experiment*. 



tmrnt 20. Place a few sheets of paper between 

 the two points of the universal discharger, and pass 

 charge through them. The mechanical effect will be so 

 groat as to perforate them with ease. 



riment 27. Place a piece of loaf-sugar on the 

 table, and bring the ends of the discharging rod in 

 contact with it on its opposite sides. The charge will 

 pass through the sugar if the points be closely pressed 

 on it, and it will be shivered into pieces. A beautiful 

 phosphorescence will be noticed if the experiment IKJ 

 tried in the dark. A piece of dry wood, if similarly 

 placed, may easily be broken to pieces. 



Exptrimcnt 28. Cork tightly one end of a narrow 

 glass tube, and insert a wire in the cork, so that its two 

 ends may be respectively inside and outside ; and having 

 filled the tube with distilled water, cork up the otlu-r 

 end, with a wire also inserted in the cork, and let the 

 two wires be separated to a short distance in the tube 

 from each other. Place this on the table of the dis- 

 charger, and bring the two rods in contact with the two 

 wires of the tube. If a charge from the battery be now 

 effected, the tube will be burst into pieces, owing partly 

 to the mechanical expansion of the liquid, the effects 

 of the heat generated, and the partial decomposition 

 which the water undergoes. We annex an engraving, 

 which will assist the student in carrying out the experi- 

 ment (See Fig. 31). 



Flf. 1L. 



We must here warn our readers, that core should be 

 taken lest the pieces of glass be driven into the face of 

 the experimenter : a small iron cage placed over the 

 tube is a prudent precaution. 



,1/1. lit 29. A very pretty luminous effect is 

 produced by sending the battery charge through a piece 

 of alum. This is best done by boring a hole on each 

 side of the salt, so that when the points of the rod of 

 the discharger are inserted, they may be at a distance 

 of a quarter of an inch from eacli other. On the dis- 

 charge being effected, the alum will become beautifully 

 illuminated, and be broken to pieces. 



In the preceding experiments we have chiefly ob- 

 served the mechanical and luminous effects of frictional 

 electricity ; we will, therefore, give some instances in 

 which the calorific effects of the force are manifested. 



Ej-fxriment 30. Connect the two rods of the uni- 

 versal disc-harder by means of a very fine piece of steel 

 wire, about six or eight inches in length, and send the 

 charge of the battery through it. The wire will be 

 instantly melted, and will full down in fine globule-*. 

 Steel and other metallic wires may be thus melted. This 

 result may be obtained by a single Ley den jar, if of 

 about three pints capacity : the wire is to be attached 

 to one knob of the common discharger, and so may be 

 brought into contact with that of the inside of the jar ; 

 the other knob of the discharger must rest against the 

 outside of the Ley den jar. 



Experiment 31. A gas-lamp, or newly-blown-out 

 candle, may easily be ignited by means of the battery. 

 The ordinary discharger must have one knob in contact 

 with one belonging to the jars of the battery, and the 

 other knob is to be brought nearly into contact with the 

 gas jet. A wire should stretch from the metal pipe to 

 the outside of the battery. 



These experiments will be sufficient to illustrate some 

 of the mechanical and other effects of a powerful elec- 

 tric charge. We shall now proceed to put our remarks 

 to a practical purpose, by referring to the use of 

 uiiH conductors in protecting tall buildings, chim- 

 neys, suwples, masts, etc. 



