Experiments on the Oxidation of Metals hy EleSlncity. 141 



This lad experiment was repeated with wires of a lefs diameter, with nearly the fame 

 refult; the five difcharges produced a diminution, which caufed the mercury to rife 

 between three and four inches. 



The refult of the lad experiments induced me to try receivers of a ftill lefs diameter ; fo 

 one of •j'^ inch diameter, and eight inches long, was taken; but on account of its fmall- 

 nefs of diameter, no more air could be exploded than the length of the tube, without ad- 

 miffion of frefli air. 



EXPERIMENT X. 



Accordingly, one difcharge of the fame degree of force was directed by the eledrometer 

 through one length of wire -^ inch diameter. 



Inches. 

 The mercury gage rofe -----. o^^^ 



Second difcharge through wire of -5^ - - - 3-,^ 



Third . - - - -jij. - - - -, 3^^^ 



Fourth . _ - . ^4^ . - > 3 



3 



The wire through which the firft difcharge was diredted, was only converted into 

 a numberlefs fmall particles, retaining their metallic luftre. The fecond, which fliewed 

 the greateft degree of abforption, was but jufl: converted into powder, mixed with particles 

 of lead. The rcfidue of this air was tried by flame, in aglafs five inches high, and one and 

 a quarter diameter, but at the mouth only three quarters, and the candle was extinguilhed 

 in it nine times. 



Thefe experiments, I think, will be found fufEcient to fliew that the fmaller the diameter 

 of the receiver in which lead is calcined by an eleftric difcharge, the greater proportion of 

 air will be abforbed, and the ninth and thirteenth experiment proves that, that which is 

 abforbed is the oxigen gas, which is by the procefs feparated from the azote of the 

 atmofphere. 



It is well known that metals require certain degrees of temperature to give them the 

 property of abforbing the greateft quantity of oxigen gas; this is the point which I had ia 

 view when I ufed wires of different diameters, becaufe I know no way hovy to increafe the 

 temperature communicated by an eleftric difcharge to metallic wires, but by diminifhing 

 thi'ie diameters or lengths in a certain proportion, or increafing the force of the di£charge> 

 which is the i. .ne thing, and the laft experiment (hews that it makes very little difference 

 whether wire of ,;'^, or tI-c> vvhich is only half that diameter,^ be ufed, fo that it does not 

 feem here to follow the fame law as common heat. 



EXPERIMENT XI. 

 To conclude with this metal ; the firft-mentloned large receiver was taken, and 130 

 inches of wire, di sV of an inch in diameter, was prepared in the fame, beii;g nearly four 



times 



