368 



Mr. Mallet on the Physical Conditions 



by smelling, specially for gun-founding ; while all the experiments made on British irons, with 

 a very few exceptions (see E. Clarke, "Brit. Bridge," vol. i., p. 445), have been made 

 upon specimens of unmixed commercial pig-iron, as found in the market, intended for the 

 common purposes to which cast-iron is applied, and not having that peculiar balance, of 

 hardness, tenacity, and toughness, indispensable for gun-metal, but unsuitable to the pur- 

 poses for which our mercantile " makes" are intended, and incapable of being afforded 

 at the price at which these are sold. It really would appear, however, from much that has 

 latterly been written and spoken on the subject, and even by those whose authority and posi- 

 tion would presume better knowledge of the subject, that these facts have been overlooked. 

 As proving how completely the per-centage of sulphur, as well as of all other impurities, 

 depends upon the working of the furnace, the following Analyses, by Dr. Schafheautl 

 (" Revue Scien." t. xxv., p. 192, and t. vi., p. 209), are important, all made from ironpro- 

 duced by the same furnace, and in continuous blast — that of Alais, Dep. du Gard, France, the 

 specimens being taken at successive periods : — 



Per-centage of Foreign Constituents only. 



Sillcium, . . 

 Aluminium, . 

 Carbon, . , 

 Azote, . . . 

 Sulphur, . . 

 Arsenic, , . 



And as enabling a comparison to be made of the relative effects of cold and hot-blast in 

 the same blast furnaces, and these, too, worked with wood fuel only, the following analyses 

 of hot and cold-blast irons, made at Kiinigshutte and Leerbach, in Hanover: — 



