264 Translations and abstracts frotri the French. 



zinc, was completely preserved. The copper retained its 

 brightness, while the iron, tin or zinc were strongly oxidated, 



3. A simple plate of very thin mica placed between the 

 copper and the iron of the preceding experiment, promptly 

 destroyed the preserving eifect of the iron : the copper was 

 oxidated. 



4. A platina wire was placed so as to unite the copper and 

 the iron, the immediate contact of which had been bsoken 

 by the mica : the copper was again perfectly preserved, and 

 not an atom of oxide of copper appeared in the fluid. This 

 phenomenon of the preserving effect of iron, even when it is 

 not in immediate contact with the copper, and when con- 

 nected with it only by a conducting wire of another metal 

 was perfectly demonstrated by the following experiment. 



5. A plate of copper was connected by a platina wire with 

 a plate of iron, and the plates were placed separately in two 

 vases filled with sea water, while the fluids themselves were 

 connected by moistened cotton or by a syphon filled with 

 the same fluid. The copper was completely preserved — the 

 water retaining its perfect transparency — while the iron in 

 the other vessel was highly oxidated. 



6. Having kept the apparatus as last described, in action 

 during forty seven days, I took it into my head to cut the pla- 

 tina wire, in the expectation of finding the copper soon cor- 

 roded, as is commonly apparent within twenty four hours af- 

 ter its immersion in sea water. But to my great surprise, 

 the copper remained perfectly clean and bright, and the fluid 

 retained its transparency. On the fourth day I interrupted 

 the communication between the fluids by talung away the 

 cotton : this circumstance had no influence on the preserva- 

 tion of the copper — it remained perfect. Imagining at first 

 that the sea water might have lost, by the chemical action 

 which had taken place, the power of oxidizing the copper, I 

 took a small quantity of the fluid, and placed in it another 

 piece of copper, which was oxidized within the first day. 

 The water therefore had lost none of its power and the phe- 

 nomenon admits of no explanation on that ground. 



Neither had the copper lost the property of being oxidiza- 

 ble by sea water, for the same piece, placed in another ves- 

 sel of sea water was quickly attacked. It would seem then 

 that the electric preserving action which iron and sea water 

 exert upon copper, prolonged during a certain period, produ- 

 ces between the elements of the copper and those of the fluid 



