142 Experlmtnis en the Oxiclatm ef Mctah h'j EhBricify, 



times the quantity that was ufed before. This was exploded and converted into an im- 

 palpable powder by twenty feparate difchargcs, and when the gages were opened, there 

 appeared to have been no air abforbed. 



EXPERIMENT XII. 



The powder or calx laft produced, was prefcrved andput into a very fmall glafs retort, 

 with an intent to try what would happen, or what alterations would take place by the 

 application of heat. No air was given out by fuch treatment, excepting a little common 

 air, which I fuppofe was contained in the retort. The powder, which was firft of a blueifh 

 white, changed into a dark leaden colour, and afterwards into a yellowifli green; and 

 when the glafs was red hot, nearly melting the powder, was only partially melted Into 

 lead. 



Laftly, twenty-four grains of this powder, which had abforbed no oxigen, was taken 

 and put into a clean crucible, with a cover to it, fet in a furnace, and kept in a white 

 heat about one hour. When taken out, there was found in the bottom of the cruci- 

 ble a perfe(9: clear glafs of a redifh brown colour. Thus we find a powder obtained 

 which pofleflcs the moft diftinguifliing properties of an oxide of lead, though it appeared 

 to have abforbed no oxigen in its preparation. 



Lead burns with a yellowifli flame by the eleflric difcharge. 



Thefe experiments appear to be fufficient to prove, that the abforption of the oxigen 

 gas from the atmofpherical air, by the powder thus produced, wholly depervds upon the 

 diameter of the receiver wherein the procefs was carried on. For we find by the tenth 

 experiment, that when eight inches of wire were calcined in a receiver only y*^ of an 

 inch diameter, it then abforbed half a cubic. inch of air. In this proportion the wire laft 

 calcined fhould have abforbed fixteen times that quantity, and the refult was that it had 

 abforbed none ; the reafon of which I muft own I do not underftand. 



Thefe experiments were made in the winter feafon, when the temperature of the 

 atmofphere was feldom lower than 28°, and not higher than 45°, and the refult was as 

 mentioned ; but not being able to reconcile myfelf to fuch paradoxical refults, I fhowed 

 the experiments to feveral philofophers, who, however, were equally as much at a lofs 

 to account for the refult as myfelf. 



On the 10th of May, 1798, I was favoured with the company of fome gentlemen of 

 the Royal Society to fee the experiments. I ufed only two receivers, one of an inch 

 4iametcr, and the other of fix inches diameter, as follows : 



EXPERIMENT XIII. 



A piece of leaden wire, of nine inches long, and ^s of an inch in diameter, was cjr- 

 j)loded by an electric difcharge in the receiver of one inch diameter. After it had laid 

 in water three minutes, the mercury gage rofe il- of an inch, which was a degree of 

 diminution of about half a cubic inch. 



EXPERIMENT 



