MECHANICS AND USEFUL ARTS. 63 



antiquities are much more frequently found than those of iron ; for the 

 obvious reason, that bronze resists, much better than iron, destruction by 

 oxidation. Although, I think, there are reasons for supposing that iron 

 was more extensively used by the ancients than seems to be generally ad- 

 mitted ; yet, in the specimens in question, it appears to me most probable 

 that the iron was used because it was required in the construction. And 

 if this be so, the Assyrians teach a lesson to many of our modern archi- 

 tects and others, who certainly do not always employ metals in accordance 

 icitk their special properties. The instrument under consideration, it will 

 be borne in mind, was one of the feet of a stand, composed of an iron 

 ring resting xipon vertical legs of bronze. A stand of this kind must 

 have been designed to support weight, probably a large cauldron ; and it 

 is plain that the ring portion should therefore be made of the metal having 

 the greatest tenacity r , and the legs of metal adapted to sustain vertical or 

 superincumbent u-eight. Now this combination of iron and bronze exactly 

 fulfils the conditions required. I do not say that a ring of bronze might 

 not have been made sufficiently strong to answer the purpose of the ring 

 of iron ; but I do say that, in that part of the instrument, iron is more 

 fitly employed than bronze. Moreover, the contrast of the two metals, 

 iron and bronze, may also have been regarded as ornamental." 



CHEMICAL EXAMINATION OF IRON SPIKES, COATED WITH COPPER, 

 BY THE PROCESS PATENTED BY E. G. POMEROY. 



The following is a report of a chemical examination of the above arti- 

 cles, made by Dr. A. A. Hayes, of Boston : 



This invention presents some peculiar features, when compared with 

 the ordinary modes adopted for coating metals. It is well known that tin 

 plate is manufactured by dipping thin sheets of clean refined iron into hot 

 melted tin, until, by repeated immersions, the surface of the Iron becomes 

 more or less thickly coated. The particles of tin adhere to the iron, with- 

 out any more than the most minute film of alloy of iron and tin being 

 formed. By the process of Mr. Pomeroy, the surfaces of the clean iron 

 spikes have first a coating of copper deposited on them galvanically, and 

 this covering adheres in consequence of a polarized condition of the par- 

 ticles of the iron. If the iron were absolutely pure, a perfectly uniform 

 crystalline covering of copper would exist over every part of the surface. 

 The metal is then protected by a coating or flux, and is immersed in a 

 bath of pure copper, or yellow metal, kept perfectly fluid, until its sur- 

 face is covered more or less thickly with copper or yellow metal. In this 

 way, reliance is not placed upon a mere coating by adhesion, which could 

 be easily removed ; but the unlike metal, iron, is previously covered with 

 copper, and this new surface unites to the metal in a fluid state, precisely 

 as amass of copper would, if it were immersed in a melted portion of the 

 same metal. This method forms the basis of a new art in working metals , 

 and the value of a single application has been tested, as follows : 



