40R 



ELECTRICITY. 



On .! el'- 



fccttof 



N ^- 



PLATE 

 CCXLVI. 

 Fig. 6. 



On the ef- 



fccts of elec- 

 tricity in fa- 

 ting mcul. 



Kin. S. Into a clean wine plans well dried on the 

 outxitle, and nearly full of water, pour a stratum of 

 ether, which will of course lie u|M>n the surface of the 

 water. When the water is connected with the electri- 

 fied conductor, and the knuckle presented to the sur- 

 face of the ether, the spark which passes from tlie wa- 

 ter to the knuckle will inflame the ether. 



Exp. 4. Fix a small cartridge containing gunpow- 

 der upon a metallic wire, insulated at the extremity of a 

 handle of glass or baked wood, and having presented 

 the cartridge to the knob of a charged Leyden phial, 

 the gunpowder will be exploded. 



1.5. In order to light a candle by electricity, 

 thrust a wire up the middle of the candle to within a 

 little distance of the wick, and having connected by a 

 chain the outside coating of a charged Leyden jar with 

 the lower extremity of the wire, bring the knob of the 

 jar to the wick, and the candle will instantly be lighted. 

 This experiment is represented in Plate CCXLVI. Fig. 6. 



EJCP. 6 In order to light a candle without a wire pe- 

 netrating it, wrap some loose cotton over the end of a 

 long brass pin or wire, and roll the cotton in some fine 

 powdered rosin. Having then charged a jar whose 

 knob is bent outwards, so as to hang a little over the 

 body of the phial, apply the naked extremity of the 

 wire to the external coating, and the cotton end to the 

 projecting knob,and the rosin, and consequently the cot- 

 ton, will be set on fire,and will burn long enough to light 

 candle. This experiment is by M. Ingenhousz, who re- 

 commends the use of the powder of white or yellow ro- 

 sin. If the cotton is dipped in oil of turpentine, the same 

 effect will be produced by the aid of a larger jar; and it 

 is singular, that the inflammation of theturpentine will be 

 assisted by strewing upon it fine particles of brass dust. 



The power of electricity in fusing metals was first 

 observed by Dr Franklin, who placed thin pieces of 

 th'm between two plates of glass bound fast together, 

 and then passed an electric shock through them. The 

 plates of glass were often shattered by the discharge ; 

 and when they remained unbroken, they were covered 

 with metallic stains. A piece of gold leaf was thus dri- 

 ven into the pores of the glass, so as to be protected 

 from the action of the strongest aquaregia. Fine gold 

 made a reddish stain, and silver a greenish one. Mr 

 Kinnerslcy, in the presence of Dr Franklin, exploded a 

 case of bottles through a fine iron wire. The wire ap- 

 peared at first red-hot, and then fell into drops, which 

 assumed a spherical form like small-shot. Mr Canton 

 repeated this experiment, and found that with a case of 

 35 bottles, he could entirely destroy brass wire 1 -330th 

 of an inch in thickness. Beccaria succeeded in melting 



small stripes of metal*, without placing them between 

 pane* of glass; and he imagined that all metals impres- 

 sed the same colours upon a surface of glass, Dr Priest- 

 Icy having f;iilc<l in repeating Mr Canton's ex periments, 

 In- inclosed the wire in small tubes of glass, and having 

 sent through them thecliarjrc ot'.-i liattery ofS^squarefeet, 

 the w ire was melted into globules of various sizes. He 

 al>o inclosed his wires in paper; and on one occasion he 

 melted an iron wire l-70th of an inch in diameter with 

 the same battery. 



Dr Priestley likewise succeeded in melting pieces of 

 leaf brass, and driving them into the surface of the 

 glass, so as to give them a metallic tinge. For this 

 purpose he took three pieces of glass, and placed one of 

 them on each side of that to which he proposed to 

 communicate the tinge. A piece of leaf brass was 

 then placed on each side of the middle plate. He then 

 sent the charge of a battery through the two stripes 

 of leaf brass, which projected a little over the glass 

 plates. The upper ana lower pieces of glass were shaU 

 tered to pieces ; but the middle piece being equally af. 

 fected on both sides, remained unbroken, and had both 

 its sides covered with a metallic tinge. These metallic 

 colours have l>een employed to impress letters or orna- 

 ments on paper and silk. " The outline of the requi- 

 red figure," says Mr Singer, " is first traced on thick 

 drawing paper, and afterwards cut out in the manner 

 of stincil plates. The drawing paper is then placed 

 on the silk or paper intended to be marked, a leaf of 

 gold is laid upon it, and a card over that ; the whole is 

 then placed in a press or under a weight, and a charge 

 from a battery sent through the gold leaf. The stain 

 is confined by the interposition of the drawing paper to 

 the limit of the design, and, in this way, a profile, a 

 flower, or any other outline figure, may be very neatly 

 impressed." 



The most accurate experiments on the fusion of metals 

 byelectricity have been made by MrBrooke.VanMamm, 

 Kienmayer, MrCuthbertson,and Mr Singer. The object 

 of Mr Brooke was to determine the relation between the 

 force of a battery and the quantity of wire which it was 

 able to fuse. Mr Singer recommends as the best wire 

 for experiments of this kind, the finest flatted steel wire 

 sold at the watch-maker's tool shops, by the name of 

 watch pendulum wire. The circuit between the two 

 coatings of the jar should be made as short as possible, 

 and the wire should be placed in a straight line, and 

 confined at the ends between small wire forceps. We 

 have condensed the results obtained by Mr Brooke into 

 the following Table. The two last experiments but one 

 are by Mr Cuthbertson, and the last by Mr Singer. 



Descriptive 

 Klectncity. 



On thcrf- 

 fecupf'elee- 

 truiiy in 

 fu*ing me- 



' 



Brookc' 

 experi- 

 ment!. 



Brooke'* 

 ex peri- 

 menu. 



TABLE containing tfie remits of Mr Brooke's Experiments on the Fusion of Metallic Wire*. 



