140 Experiments on the Oxidation of Metals by EleBn'ctiy, 



EXPERIMENT VII. 



■ Inftead of the laft-mentioned receiver, Fig. 4, was taken a glafs tube, of about one 

 inch diameter, and nine inches long,* and furnifhed with lead wire of ^V inch diameter, 

 being the fame as that ufed in the three firft experiments. After it had been placed in 

 water, with the cock only above the furface and open ; and it had remained three minutes, 

 the cock was (hut, the inllrument taken out and wiped dry, one end of it was annexed 

 to the chain h, of the eledlrometer, and the other end to the chain which was in com- 

 munication with the outfide of the battery, the fame ftrength of charge was direfted 

 through the wire, by the elecSlrometer, as in the laft experiments, and the fame kind of 

 powder with refpeft to colour appeared ; the inftrument was again laid in the water, with, 

 the cock above the furface, and the water gage was fcrewed on to the cock ; when three 

 minutes were expired, the cock was opened, and there appeared fo extraordinary diminu- 

 tion of air, that the water in the gnge run over ihe upper bend into the inftrument : this 

 diminution appeared fufficient to make a mercury gage fenfible. 



The inftrument being cleaned, and provided with thirty- five inches of wire of the 

 fame diameter as above, five feparate difcharges were direded through the wire ; feven 

 inches were exploded at each difcharge, and the fame procefs with refpetSl to laying of it ia 

 water before and after each difcharge was obferved ; and the 



Inches. 

 Firft difcharge caufed fo extraordinary diminutioji, that the 



mercury rofe in the gage - . - . - i ■ 



Second difcharge » __--.- i_^ 



Third Ot'tt 



Fourth _._------ 0/5 



Fifth o^'^ 



In the whole ■3>i% 



■which is nearly equal to two cubic inches. The contents of the whole inftrument was 

 nine cubic inches. 



The air thus diminiflied in the Inftrument was left ta ftand till the fame hour next day ;, 

 but on opening the cock no further diminution had taken place. 



The purity of this refidue of air was tried by the teft of flame, and it extinguiftied 

 a candle eight times. Azotic gas, in the fame glafs, extinguiftied the fame candle ten 

 times, fo that all the oxigen gas contained in that quantity of atmofpherical' air was nearly 

 abforbed ; the powder produced was nearly fame as that in the large receiver. 



• It was mounted in the fame mannei^as Fig. 3, excepting that on account of it« diameter only one.aJr 

 cock, and gage was ufed» 



This 



