OperAiion of the Pile ef/foUa in difftrent Gajis. 8*5 



Experiment 8. By ihe 7th experiment contained in my letter of the 24th of June, it 

 appears that a galvanic apparatus is not capable of ailing in a Boylean vacuum *, In this 

 experiment, I introduced into three feparate glafs receivers (of 1 foot 3 inches in height, 

 and 5.5 inches diameter) placed over water, three galvanic apparatus, each of forty half 

 crowns with zinc, and the difcs foaked in pure water. The firft receiver was full of at- 

 mofpheric air j the fecond had been filled with oxygenous gas prepared from manganefe 

 and fulphuric acid ; and the third contained azotic or nltrogene gas, which had been ob- 

 tained by leaving a mixture of i .5 ounces of iron filings, with fulphur in it for five days, 

 during which time the water had rifen in it about four inches. Three glafs tubes filled 

 with pure water as before, and with copper wires, were joined to brafs wires, which had 

 been prevloufly fixed to the bafes of the apparatus, and pafling under the bottom of the re- 

 ceiver, were extended above the furface of the water in the clfterns. 



The refult of this experiment was, that the copper wires attached to the apparatus In 

 the receiver filled with atmofpheric air, produced oxide and gas as ufual, but not in fuch 

 quantities as when the apparatus has free accefs with the external air. The wires attached 

 to the apparatus in the receiver of oxygenous gas, formed gas and oxide moft copioufly, 

 even part of the brafs wire attached to the zinc bafe, depofited much oxide within the re- 

 ceiver. The wires attached to the receiver of azotic gas, produced neither oxide or gas, 

 and the galvanic apparatus had no apparent efFeft. 



The tubes after remaining twenty hours were removed, and new wire attached to the 

 apparatus in the receivers containing atmofpheric air, and the oxygenous gas ; but they 

 produced only a faint cloud In the water. The water had rifen in the receiver, which ma- 

 nifeftly Indicated a diminution of the original quantity of air. 



CONCLUSION. 



From this experiment, and from the examination of the ftate to which atmofpheric air 

 is reduced in a glafs receiver, placed over a galvanic apparatus and confined by water, I 

 think we may venture to agree in opinion with Cit. Fabroni, (Phil. Journal, vol. Ill, 

 p. 308) that the efFe£ts of galvanifm depend on a chemical operation, and are produced 

 principally by the attra£lion of oxygen from the atmofphere, and therefore, on the prefent 

 theory, the whole operation can be received only as a combuftion fimilar to that which 

 arifes from the combination of fulphur, and iron filings with water. 



I remain. Sir, 



with much eftecm, 



your moft obedient, 

 humble Servant, 

 Croydon, Jug. 3, 1800. HENRY HALDANE. 



I have fubmltted to examination fulphur and iron filings, In the apparatus I ufed for 

 the quickfilver ; but I do not perceive that that combination produces any eifeft as a gal- 

 vanic apparatus. 



* Vide Mr. Boyle's Letter to Lord Dungarvon, pnge 10, Quarto. 



Invefligation. 



