Defer tption of a newly invented Galvanometer. 4 1 



making feveral a littlcjdiffcrent from any I have vet heard of, 

 and in all of them I have found the galvanometer fo ufeful 

 an inftrument, that: [ ean reeonimend it with {pine confi- 

 dence-to thofe who are fund of fucti experiments. 



I (hall not encroach upon the pages of the Philofophioal 

 Magazine by detailing the remits of experiments in which 

 others have anticipated me ; but (hall, as briefly as poffible, 

 ftate a few experiments respecting the action of the galvanic 

 pile on feveral of the gates, which prefent foine new facts on 

 this interellino; fubject. 



In thefc experiments an exhaufted transfer was fcrevved 

 upon the top of a oraduated glafs cylinder, open at the bot- 

 tom. The cylinder being filled with water and placed over 

 a pneumatic tub, was then charged with gas to any particular 

 diviiiou, and the divifion noted, by which means the quantity 

 allowed to afcend into the transfer, upon opening a cock in> 

 tcrpofed between it and the cylinder, was known; and eon- 

 fequently, whether any or what quantity of the gas under 

 experiment was abforbed by the procefs. 



L The pile being placed, with a I'm all tube containing 

 di (tilled water, and connecting wires of fine filver, in the 

 exhaufted transfer, the quantity of atmofpheric air admitted 

 from the adjoining graduated cylinder was regitiered. After 

 (landing in this way for 36 hours, out of 200 cubic inches of 

 atmofpheric air, 40 were found to have been abforbed. During 

 the whole time of the abforption, gas was formed in the final! 

 tube of water, and a floculent oxyd was precipitated. 



II. When oxygen gas, obtained from the oxymuriat of 

 potafli, was ufed, the power of the pile was confulerablv in- 

 creafed ; the one wire gave out gas more rapidly, while a 

 much more copious floculent precipitate was formed by the 

 other. Leaving this experiment during the night, 200 cubic 

 inches of oxygen were found tq have been abforbed by the 

 morning. Water had afcended from the pneumatic tub, and 

 not only filled the graduated cylinder, but rifen fo high into 

 the transfer, that the pile was half immerfed in it. The ex- 

 hauftion, thus produced, maintained a column of water of 

 about 16 inches in, height. 



III. Azotic gas, procured by the decompofition of atmo- 

 fpheric air by the fulphuret of potafh, totally (topped the 

 action of the pile, neither gas nor precipitate appearing in 

 the fmall tube of water. 



IV With hydrogen gas the effect was the fame. I could 

 not perceive that the pile had the final left action. 



It is proper that I mould obferve here, that the cloths in- 



terpofed between each pair of metals in thele experiments 



A . were 



