170 Mr. Mallet on the Physical Conditions 



results of charcoal smelting and refining, it was remarkable that in the Belgian 

 Departments of the Exhibition of 1851, the MBR. Ardennes charcoal-iron, cer- 

 tified " never to have produced a musket-barrel that burst," stood beside the coke- 

 made iron wire of Orban and Sons, certified to stand a strain of above 40 tons 

 to the square inch. The experiments made on the SamakofiP and Elbese char- 

 coal irons, and recorded (Proc. Ins. Civ. Eng., vol. iii. p. 225), prove also their 

 great inferiority in strength and elasticity to the vast mass of British makes. 



Some valuable Tables of comparative strength of French with British and 

 foreign wrought-irons may be found in a Paper by M. Martin (" Du Fer dans les 

 Fonts Suspender," &c. Ann. des Mines, Sieme Ser., t. v. p. 68). These experi- 

 ments were made by Colonel Barbe and M. Bornet, at the Iron Works of Cha- 

 mond and of Fourchambault. 



It would be tedious to quote these authorities even in extract ; but the re- 

 sult may be given in the words of MM. Flachat, Barrault, and Petiet, in sum- 

 ming up these experiments: — " The mean resistance of these irons (the best 

 that France, at the time (1845) could produce) is about 35 kilos, to the square 

 millimetre ; and cable irons being always made with much care, are therefore 

 stronger than the majority of ordinary irons, while the experiments made in 

 England by Telford and Brunei give resistances of from 40 to 50 kilo, to the 

 square millimetre." — Fabric, de la Fonte et du Fer. 



67. It has been repeatedly proposed and abortively attempted to improve the 

 quality of cast-iron for guns, by the admixture of some foreign metal in minute 

 proportion. Copper, it was affirmed by Hassenfratz long ago, added much to 

 the tenacity of cast-iron. This alloy was formed, and some experiments made 

 on it by the younger Bramah, as recorded by Tredgold, and it is afiirmed to 

 have been adopted by Perkins, for closing the porosity of cast-iron when ap- 

 plied to the cylinders of hydraulic presses. Tin, lead, tungsten, manganese, 

 have also been tried, but none to any good purpose, nor could any be justly 

 anticipated ; the affinities of iron in forming alloys are very slight, and its pre- 

 vious combination with carbon, for which it possesses so powerful an affinity, 

 seems to reduce the former to so low a point that its alloys are little better 

 than heterogeneous mixtures which separate by eliquation on cooling. 



68. Want of assured homogeneity, especially in large masses, appears also 

 to be the objection to " Stirling's patent toughened iron," i. e. wrought-iron fused 

 in mixture with cast-iron, nor is it easy to see how his method gives a result 



