294 EIGHTH REPORT 1838. 



with brass in some way, and that its preservation had fol- 

 lowed. 



100. The statement created considerable discussion and atten - 

 tion at the time, and at first seemed to Professor Davy and myself 

 an important element in the subject of investigation with which 

 we had been entrusted by the Association. Accordingly, very 

 soon after the meeting, Professor Davy addressed Mr, Hartley- 

 upon the subject, detailing the results of his previous experi- 

 ments, and expressing his conviction of the non-protective pow- 

 er of iDrass to iron, and assigning another and sufficient cause 

 wholly unconnected with electro-chemical protection to the phe- 

 nomena described by Mr. Hartley. A copy of his letter is an- 

 nexed, as published in Saunders' News-letter of Oct. 24, 1837. 



"To John B. Hartley, Esq., Liverpool. 



" Royal Dublin Society's Laboratory. 



" Sir, 



" You will I am sure excuse the liberty I take in addressing 

 you, on an interesting and important subject on which you have 

 recently been engaged, namely, preventing the corrosion of cast 

 and wrought iron in salt water : I also have made many experi- 

 ments with a view to the same object. I have to express my 

 regret that the state of my health prevented me from taking an 

 active part in the proceedings of the Chemical Section at the 

 late meeting of the British Association for the Advancement of 

 Science in Liverpool. I was not present when your paper " On 

 preventing the corrosion of cast and wrought iron in salt water" 

 was read and discussed. The object of it, as reported in the 

 only two public prints I have seen, namely, Saunders' News- 

 letter of 15th Sept., and the AthenaBum of the same date (the 

 former of which I only saw yesterday), was to prove that brass 

 protects cast and wrought iron from corrosion in salt water, 

 without being itself corroded. It was also stated, that the iron 

 so protected remained in excellent preservation after a period of 

 twenty-five years. I must confess that these statements appear- 

 ed to me to be not only anomalous, but in direct opposition to my 

 own experiments. I have no hesitation in stating, as the result 

 of my experience, that brass will not protect cast or \vrought 

 iron or steel from corrosion, either in salt or fresh water ; but, 

 on the contrary, these metals will protect brass from corrosion 

 under 6'uch circumstances, at least for a limited time. 



" I need not tell you that if brass were found to protect cast 

 and wrought iron in salt water, suppose for ten days, the pre- 

 sumption would be, that it would do so for twenty-five years ; 

 but if, on the contrary, brass will not protect iron for ten days, 



