involved in (he Construction of Artillery. 221 



form the staple material for field artillery (which, however, appears by no means 

 probable), it would be an object worthy of national undertaking and expendi- 

 ture, as being utterly beyond the reach of private effort, or the demands of 

 commerce. 



154. The circumstances of chief difficulty and importance, in the manipula- 

 tion of gun-metal, as affecting the production of cannon, are : — 



1°. The chemical constitution of the alloy, as influencing the balance of 



its hardness, or , ° ../ , and tenacity. 



2". Its chemical constitution, and what other conditions, influence the 

 segregation, of the cooling mass of the gun when cast, into two or 

 more alloys, of different and often variable constitution. 



3°. The effects of rapid and of slow cooling, and of the temperature at 

 which the metal is fused and poured. 



4°. The effects due to repeated fusions, and to foreign constituents, in 

 minute proportions entering into the alloy. 



155. These questions have been more or less considered by Antoni, Birin- 

 goccio, Briche, Dartein, Schlie, Lamartilliere, Monge, Darcet, Andreossi, Dus- 

 saussoy, Gay-Lussac, Moriz Meyer, De Massas, and others, but by none syste- 

 matically. 



156. Omitting the older guns, which almost always consisted of a heteroge- 

 neous mixture of copper and tin, with zinc, lead, antimony, cobalt, nickel, silver, 

 and iron, or one or more of these ; all modern gun-metal comes to be some 

 particular case of the general formula (Cuj;-f Suj,). 



157. The following Table, extracted from the author's SecondReport onlron 

 (Trans. Brit. Assoc, vol. ix.), contains the results of a carefully conducted series 

 of experiments made by him on the chemical constitution and physical proper- 

 ties of a number of such binary alloys. A few additions have been made of 

 alloys, remarkable or important in their mercantile, or other relations, so far as 

 their properties have been ascertained. 



It is astonishing to find that, after five hundred years' habitual use of the 

 material, the military literature of Europe appears barren of a single series of 

 systematized and accurate experiments on the physical properties of gun-metal. 

 Nor has America produced such, although in advance, by the skill and energy 

 devoted to the improvement of its ordnance, which its numerous Government 

 Reports display. 

 VOL. xxm. 2 G 



