1824.] Copper Sheeting by Sea Water, fa. 97 



far from its surface being corroded, in many parts there was a 

 regeneration of zinc or of iron found upon it. 



6. In pursuing these researches, and applying them to every 

 possible form and connexion of sheet copper, the results were of 

 the most satisfactory kind. A piece of zinc as large as a pea, 

 or the point of a small iron nail, were found fully adequate to 

 preserve forty or fifty square inches of copper; and this, where- 

 ever it was placed, whether at the top, bottom, or in the middle 

 of the sheet of copper, and whether the copper was straight or 

 bent, or made into coils. And where the connexion between 

 different pieces of copper was completed by wires, or thin fila- 

 ments of the fortieth or fiftieth of an inch in diameter, the effect 

 was the same ; every side, every surface, every particle of the 

 copper remained bright, whilst the iron or the zinc was slowly 

 corroded. 



A piece of thick sheet copper, containing on both sides about 

 sixty square inches, was cut in such a manner as to form seven 

 divisions, connected only by the smallest filaments that could be 

 left, and a mass of zinc, of the fifth of an inch in diameter, was 

 soldered to the upper division. The whole was plunged under 

 sea water; the copper remained perfectly polished. The same 

 experiment was made with iron : and now, after a lapse of a month, 

 in both instances, the copper is as bright as when it was first 

 introduced, whilst similar pieces of copper, undefended, in the 

 same sea water, have undergone considerable corrosion, and 

 produced a large quantity of green deposit in the bottom of the 

 vessel. 



A piece of iron nail about an inch long was fastened by a 

 piece of copper wire, nearly a foot long, to a maes of sheet cop- 

 per, containing about forty square inches, and the whole plunged 

 below the surface of sea water ; it was found, after a week, that 

 the copper was defended by the iron in the same manner'as if it 

 had been in immediate contact. 



A piece of copper and a piece of zinc soldered together at one 

 of their extremities, were made to form an arc in two different 

 vessels of sea water ; and the two portions of water were con- 

 nected together by a small mass of tow moistened in the same 

 water: the effect of the preservation of the copper took place in 

 the same manner as if they had been in the same vessel. 



As the ocean may be considered, in its relation to the quan- 

 tity of copper in a ship, as an infinitely extended conductor, I 

 endeavoured to ascertain whether this circumstance would 

 influence the results ; by placing two very fine copper wires, one 

 undefended, the other defended by a particle of zinc, in a very 

 large vessel of sea water, which water might be considered to 

 bear the same relation to so minute a portion of metal as the sea 

 to the metallic sheeting of a ship. The result of ihis experi- 

 I was the same as that of all the others; the defended 



New Scries, vol. vi it. ii 



