1843.] on the effects of Sea-water on Iron. 1079 



nature, called the attraction of affinity, metals and all kinds of simple 

 matter are disposed to join and form compound bodies with other kinds 

 of matter in their immediate neighbourhood, and even when thus com- 

 bined, if placed under favoring circumstances, compound bodies will 

 frequently dissolve spontaneously intimate and very close relations, to 

 assume new and totally different combinations with other substances ; 

 the only explanations for which, in our present state of knowledge, 

 is, that in such cases, the elementary bases of the compound bodies are 

 said to have a greater affinity or pre-disposition to join with the latter, 

 than their former co-constituents, thus the carbonate of soda is disin- 

 tegrated, and the union dissolved between the carbonic acid and the 

 alkali soda, if it be placed in juxta-position with tartaric acid, for 

 which soda has a greater affinity than it has for the carbonic acid ; but 

 to proceed would be to write a chemical lecture, and I will therefore 

 terminate this otherwise endless digression, and return to my subject, 

 by observing, that it requires the presence of very particular circum- 

 stances to produce any metal in a purely native state. The general 

 rule is, that they are extracted from the earth in the condition of 

 pyrites or salts, that is, in combination with oxygen, or some one of the 

 various mineral acids, and from these salts, by the process of fusion, 

 the different metals are reduced to the pure or working state. 



After all the labor, however, bestowed upon them, the general ten- 

 dency of metals is to return to their original condition of compound 

 salts, and more than all iron seems disposed to this chemical alteration 

 of structure, deriving readily from air, earth, and water, the necessary 

 co-constituent oxygen, whilst fire only increases the intensity of at- 

 tractive affinity, and thus accelerates the operation, so that all sur- 

 rounding nature seems opposed to its remaining long in that metallic 

 state which renders it at all useful or profitable ; and as iron is daily 

 becoming more and more employed for the purposes of mankind, it is 

 an object of considerable moment to lessen as much as possible the 

 vast expense, occasioned by the continually required replacement of 

 the corroded or oxydized metal. 



This, it is found, can be easily accomplished by opposing one law of 

 nature to another, or in other words, antagonizing chemical affinity on 

 the one hand, by electro-galvanism on the other, the best demonstrable 

 proof of which operation is the well-known suspension of chemical 



7 c 



