EFFECTS OF KLECTRICITY AND HEAT. 



8i 



at the utmoft, was eflimated to referable that of the boiling 

 point of water. If eledricity liquefied metals and brought 

 them into conibuftion by the heat it excites, the platina wire 

 muft, after a fhock. which differed but little from that which 

 would have produced its difperfion and its combuflion, have 

 approached the degree of temperature which occafions its !i- 

 quefaclion : now this degree, which is the moft elevated that 

 can be obtained, would, according to the valuation, more or 

 lefs accurate, of Wedgwood, be 32277° of Fahrenheit. 



When the Qiock is (ufficiently ftrong to defiroy the aggrega- Elearicltv de- 

 tion of the platina wire, it begins by detaching moleculas from taches the parts 

 its furface, which exhale like fmoke ; if it is flrong enough to ^^^^ ^^^ jyfg j^^ 

 produce combuftion, the remains of the wire appear to be torn 

 into filaments. 



A thermofcope, blackened with ink, and placed in the ftream The eledlric 

 of a ftronff eledric fpark, only experienced a dilatation which current of fparks 



, 1 . /• ., . ■ caufeslittie 



was nearly equal to one degree ot Keaun^ur s thermometer- ijeat, 

 and this flight effect might depend on the oxidation of the iron 

 of the ink : placed befide the current, it did not (hew any di- 

 latation, although the air was neceffarily affe61ed by the elec- 

 tric adtion : it was the fame when it was placed in contad with 

 a metallic condu6lor which received a flream lefs powerful than 

 in the preceding experiments.* 



A cylinder of glafs filled with air, with an exciter at each of Eieftric ftock 

 its extremities, to one of which was fixed a tube, communi- t^J^rough air. 

 eating with another cylinder filled with water, produced an 

 impulfe at each fhoek which raifed the water more than a de- 

 cimeter above its level; but its effect was inftanlaneous. 



Thefe experiments feem to me to prove that eleftricity does Hence it is In- 

 not a6l on fubftances, and on their combinations, by an ele- f-rred, thatelec- 

 vation of temperature, but by a dilatation which feparates ttie by'headn^ 'b'\ 

 inoleculae of bodies. The flight heat obferved in the platina dilating. 

 wire is only the effe6t of the compreffion produced by the mo- 

 leculae which firft experience the eledric a6tion, or which ex- 

 perience it in a greater degree; it muft therefore be compared 

 to that excited by percuffion or compreffion. 



If the dilatation was the effe6lof heat, that experienced by 

 a gas in the experiment related above, would not have been 



* A fmall thermometer in the luminous current between two 

 balls of wood, is raifed 32 degrees.— Nairne, 



Vol. VIIL— June, 1804, G inftantaneous. 



