54 ANNUAL OF SCIENTIFIC DISCOVERY. 



pared with iron, was counterbalanced by the vast amount of time and labor 

 which must have been bestowed on the construction of the old wrought-iroa 

 guns. 



Although cast iron was applied to the production of shot and other pro- 

 jectiles at the close of the fourteenth century, it was not until about 1000 

 that cannon were made of this material. In proportion as the facility of its 

 production increased, its application in this direction was gradually ex- 

 tended; but in no country has it ever entirely superseded bronze or gun- 

 metal, which, on account of its superior tenacity, has always been employed 

 for the construction of light field-guns. This alloy possesses, however, some 

 very serious defects, arising principally out of its softness, and its consequent 

 incapacity to resist the injimous effects of rapid firing. Numerous experi- 

 ments have been made with alloys of copper, and, recently, with other com- 

 binations of that metal, with the object of discovering some material at least 

 equal to gun-metal in tenacity, and superior to it in hardness and also in 

 uniformity. Alloys of copper and aluminum have been proposed; but, 

 apart from the present great cost of aluminum, the readiness with which 

 this metal is attacked by alkaline substances, and the powerful corrosive 

 action which portions of the products of decomposition of powder conse- 

 quently exert upon it, preclude its application to the production of a substi- 

 tute for gun-metal. The effect of silicon in hardening and greatly increasing 

 the tenacity of copper has also received attention; and there appears little 

 doubt that, the difficulty of producing on a large scale a uniform compound 

 of copper and silicon once overcome, such a material would prove a most 

 valuable substitute for bronze. The effects of a small quantity of phosphorus 

 upon copper are similar to those of silicon; the metal is greatly hardened, 

 its uniformity may be ensured, and its tenacity is also much increased. 

 Copper containing from two to four per cent, of phosphorus will resist a 

 strain of from forty-eight to fifty thousand pounds on the square inch, while 

 the average strain borne by gun-metal is about thirty-five thousand pounds. 

 Uniform compounds of phosphorus and copper can, moreover, be prepared 

 without difficulty upon a large scale. By immersing pieces of phosphorus 

 for a short time in a solution of sulphate of copper, they become coated with 

 a film of the metal, so that they may be safely handled, and thrust beneath 

 the surface of liquid copper before the coating melts; thus the phosphorus 

 is readily combined with the copper without, loss. 



The great success which has recently attended the construction of mallea- 

 ble iron guns appears, however, to render it doubtful whether any of the 

 compounds above referred to, or others of a similar character, will ever 

 receive employment as materials for cannon. Attempts have been made 

 from time to time, for many years past, to produce forgings of malleable 

 iron of sufficient size for conversion into cannon. The great difficulty of 

 insuring anything approaching uniformity of chemical composition and 

 physical properties in cast iron, and the consequent great variation and 

 uncertainty of the enduring power of guns made of that material, acted as 

 powerful incentives for the prosecution of such experiments. Experience 

 gained during the late war was also unfavorable, partly to the employment 

 of cast iron as the material for the heaviest pieces of ordnance, and partly 

 to the system of casting those hitherto in use. 



The attempts made by Xasmyth and others to produce large forgings, 

 sufficiently perfect for conversion into cannon, were, however, uniformly 

 attended with failure, excepting in the instance of a very large gun thir- 



