& Additional Notes. 



other, as when the copper sheathing of ships was held on by iron 

 nails. And hence another great operation of nature is probably pro- 

 duced, I mean the restoration of oxygen to the atmosphere from the 

 surface of the earth in dewy mornings, as well as from the perspira- 

 tion of vegetable leaves; which atmospheric oxygen is hourly de- 

 structible by the respiration of animals and plants, by combustion, 

 and by other oxydations. 



6. The combination of the electric ethers with metallic bodies 

 before mentioned appears from the Galvanic pile; since, according to 

 the experiments of Mr. Davy, when an acid is mixed with the water 

 placed between the alternate pairs of silver and zinc plates, a much 

 greater electric shock is produced by the same pile; and an anony- 

 mous writer in the Phil. Magaz. No. 36, for May 1801, asserts, that 

 when the intervening cloths or papers are moistened with pure alcali, 

 as a solution of pure ammonia, the effect is greater than by any other 

 material. It must here be observed, that both the acid and the alca- 

 line solution, or common salt and water, and even water alone, in 

 these experiments much erodes the plates of zinc, and somewhat 

 tarnishes those of silver. Whence it would appear, that as by the 

 repeated explosions of the two electric ethers in the conducting 

 water, both oxygen and hydrogen are liberated; the oxygen erodes 

 the zinc plates, and thus increases the Galvanic shock by liberating 

 their combined electric ethers : and that this erosion is much increased 

 by a mixture either of acid or of volatile alcali with the water. Fur- 

 ther experiments are wanting on this subject to show whether metallic 

 bodies emit either or both of the electric ethers at the time of their 

 solution or erosion in acids or in alcalies. 



X. Of the twfi Magnetic Ethers. 



1. Magnetism coincides with electricity in so many important 

 points, that the existence of two magnetic ethers, as well as of two 

 electric ones, becomes highly probable. We shall suppose, that in a 

 common bar of iron or steel the two magnetic ethers exist intermixed 

 or in their neutral state; which for the greater ease of speaking of 



