ELECTRICITY. 



455 



Descriptive If the melted sealing-wax is held in the hand, at a 

 Electricity, distance from the conductor, the waxen filaments will 

 dart from the wax to the conductor, and be condensed 

 into a kind of red wool as before. 



Eip. 1 1 . Place a piece of lighted camphor in a me- 

 tallic spoon which communicates with the prime con- 

 ductor. When the conductor is electrified, the cam- 

 phor will throw out numerous ramifications, and will 

 shoot forth like a grow ing vegetable. 



Eip. 12. Take a capillary tube of such a diameter, 

 that water will not drop from it, but be retained in vir- 

 tue of the attraction of cohesion. Bring this tube near 

 an electrified prime conductor, and the water will be 

 drawn out of it and discharged in a continued stream. 

 The electrified jet sometimes divides into several 

 streams, and is accelerated in proportion to the small- 

 ness of the bore. In this experiment, the capillary at- 

 traction of the tube is overcome by the more powerful 

 attraction of the conductor. 



In all these various cases of attraction and repulsion, 

 and in every other case of electric action, two bodies 

 electrified positively repel each other, and also two 

 bodies electrified negatively, while a body electrified 

 positively always attracts a body possessing negative 

 electricity. 



SECT. V. On ihe Accumulation of Electricity. 



6n the ac- THE electrical effects which we have hitherto been 

 cumulation considering, are of the most transitory kind, and exist 

 of electri- only during the excitation of the electric. Although 

 the electricity developed by the friction of a glass tube, 

 or of a glass cylinder, was sufficiently strong for exhi- 

 biting many interesting experiments, and for the pur- 

 pose of investigating the nature and properties of the 

 electric fluid, yet it was not till the method of accumu- 

 lating electricity was discovered, that philosophers be- 

 came acquainted with the overpowering energy of this 

 extraordinary agent. 



This great step in the progress of the science was 

 made by the celebrated Muschenbroek, in his invention 

 of the Leyden phial or jar. This instrument is repre- 

 sented in Plate CCXLIII. Fig. 5, where a b is a cylin- 

 drical glass vessel, having the lower part b c coated 

 with tinfoil all around, the inside being coated in a si- 

 milar manner, and to nearly the same height. Through 

 a perforation in the piece of wood or cork which fills 

 the mouth of the jar, is inserted a brass rod ft e, ha- 

 ving a small ball of brass <l at one end, and two or 

 three inches above the top, and communicating by its 

 other end with the inside coating, by means of a chain 

 or wire. 



If the jar thus constructed is held to the conductor 

 it. of an electrifying machine, so that the knob d may be 

 about half an inch from it, a number of sparks will 

 pass from the conductor to the- knob d, and after grow- 

 ing weaker and weaker, they will at last cease. The 

 electricity from the conductor has now been accumu- 

 lated in the jar, and the jar is said to be charged. If 

 any person now holds the jar in one hand by the out- 

 side coating, while with the other he touches the knob 

 d, he will hear a sharp sound, accompanied with a bril- 

 liant flash of light, and will experience a severe and 

 most disagreeable concussion in his wrists, elbows, and 

 breast, the accumulated electricity of the jar having 

 passed through his body. This sensation is called the 

 electric shock, and the jar is said to be discharged. 



The electric shock may also be experienced by any 

 number of individuals, provided they take one ano- 

 ther by the hand, and form the line of communication 



CLIII. 



, 5. 



I of 



between the inside and outside coatings of the phial. Dcscriptiva 

 If the person at one end of the line touches the outside Electricity. 

 coating, then the shock will be felt by every individual " "~Y""" 

 that composes it, the instant that the person at the 

 other extremity touches the knob of the phial. In this 

 manner the Abbe Nollet electrified 180 of the French 

 guards in the king's presence ; and, at the Carthusian 

 convent in Paris, the whole of the religious formed a 

 line of 5+00 feet by means of iron wires between every 

 two persons, and were all simultaneously electrified 

 upon the discharge of the phial. 



In order to discharge the jar without receiving a Discharging 

 shock, it is necessary to have two circular wires fm, m, rod. 

 (Fig.6.), having knobs f,g, at each end, and connected by p LATK 

 a joint at m, where a glass handle, mn, is inserted. The CCXLIII. 

 experimenter takes hold of the glass part, and placing Fig- 6. 

 the lower knob g on the exteftial coating, the discharge 

 is effected as soon as the other knoby comes in contact 

 with d. This instrument is called a discharging rod, 

 and is represented in Fig. 5. in the act of discharging 

 the jar. 



The cylindrical form of the jar is by no means ne- Electricity 

 cessary to the accumulation of the electric fluid. The accumula- 

 same effect is obtained when a plate of glass is coated ted on plate) 

 on both sides with tinfoil, the glass extending about K* 858 - 

 two inches beyond the metal all around, as is repre- 

 sented in Fig. 7. With this plate of glass, the same Fig. T. 

 quantity of electricity will be accumulated as in a cy- 

 lindrical jar, having the same area of coated surface. 



When it is required to accumulate great quantities of Electrical 

 electricity, several of the cylindrical jars are placed in battery with 

 a box containing as many compartments as there are Jars< 

 jars. The bottom of this box, upon which the jars 

 must rest, is either covered with tinfoil or a trellis of 

 wire, so that the outside coatings of the jars will com- 

 municate with one another by means of this metallic 

 surface. The inside coatings are made to communicate 

 with each other by horizontal bars of metal passing 

 through the knobs of each jar ; a construction which is 

 represented in Fig 8. which is a battery composed of . 

 16 jars. Sometimes the wires from the inside coating, ' 8 ' 

 instead of terminating in a knob, are bent at top, and 

 inserted in one common central knob. This form is 

 shewn in Fig. 9. whicli represents a battery of nine {?; p 

 jars. 



A battery may also be constructed by a combination 

 of panes of glass coated as in Fig. 7. Dr Franklin 

 formed a battery of this kind with 1 1 panes of common 

 window-glass, and with it he made the greater part of 

 his experiments. 



Batteries of great size have been constructed by dif- pijctrical 

 ferent electricians, so as to accumulate an enormous battery with 

 quantity of electricity, capable of melting the hardest plates, 

 metals, and of putting an instantaneous termination to 

 the functions of animal life. Dr Priestley constructed 

 a battery consisting of 64 jars, and containing 32 square 

 feet of coated surface. Mr Cuthbertson completed, in 

 1784, for the Teylerian Museum at Haarlem, a bat- 

 tery of 135 jars and 132 feet of coated surface ; and in 

 17&9 he completed another battery for the same Insti- 

 tution, consisting of 100 jars, and containing 550 feet 

 of coated surface. 



Batteries are charged and discharged exactly in the 

 same manner as a single jar. If one of the knobs of 

 the battery communicates with the prime conductor of 

 the machine in a state of action, it will soon be fil- 

 led with the electric fluid ; and the discharge may be 

 effected by making a communication between the ex- 

 ternal and internal coating, by means of a discharging 

 rod, or any other conductor. 



