^g !»JRCCIPITATIdN OF OXIDES BY THEIR OWN METAI.S. 



after the cluiin was completed, a blackish gray substance 

 was deposited on the point of the zinc immersed in the so- 

 lution, and tiiis continued increasing^ for 48 hours, while a 

 grayish coat of oxide of zinc was de]>ositing on the [.art in 

 the water. The ramifications of zinc, that were ou the 

 lower part, had the aspect of an oxide; but on rubbing 

 them vvltij a hard substance they acquired the brilliancy of 

 zinc. 

 Koriateofzlnc ^^' "^^^^^^ experiment was repeated, only acidulating the 

 a' dacidulaied vvater with two drachms of muriatic acid. Tlie result was 

 nearly the same, excejxt that less zinc separated, because 

 the chain did not remain so long active, the liquors having 

 taingled too soon. 



Experiments ivith solutions of iron, water, acidulated water, 

 and iron. 



f.kccn SI 1- ^7 a^id 18. An ounce of green sulphate of iron was dis- 



»l£-rcof iron, solved in three ounces of water, and a chain was formed with 

 four ounces of water, and a bar of very soft iron. I ob- 

 served no difference between the action that took place on 

 the part of the bar in contact with the water, and that In 

 contact with the solution of iron, but in both the iron was 

 coated with a stratum of black oxide of iron, and some j'el- 

 low flocks resembling oxide separated from the solution. 

 The same effect took place when the water was acidulated 

 vith a drachm of concentrated sulphuric acid. In neither 

 of these experiments was any electric polarity observed, or 

 point ofo. 

 \-,,,;j^eof ti«. ^0' Four ounres of fuming muriatic acid were gradually 

 ititurated with pure iron filings. With this solution, four 

 ounces of water, and a bar of soft iron, a chain was formed. 

 It did not appear to have more effect than those of the two 

 preceding experiments, for no difference was observable in 

 the state of the iroir in the upper and under liquors. In 

 each the bar of iron was covered with black oxide, and 

 flocks of brown yellow oxide were gradually deposited. 

 'uriitcofirpn '20. On varying this cKperiment by adding two drachms 

 >ad<lu!..neJ of fuming muriatic acid to the four ounces of vvater, a solu- 

 tion of the iron iu the acidulated water took place, with the 



evolution 



