THE ROYAL ARTILLERY INSTITUTION. 
199 
To sliow the steel-like characteristics of bronze steel, knife blades 
were made from it, which exhibited all the properties of un-tempered steel. 
If it were found practicable to construct a gun of chilled bronze 
thus steeled as it were by pressure or forging, General Yon Uchatius 
considered that he had gained his great object, and provided Austria 
with a gun metal which would render her independent of foreign 
manufacture. 
Before attempting the actual construction of a bronze steel gun, 
however, it was necessary to find out what were the proportions of tin 
and copper best suited for chill casting, and further how it was possible 
to give to the inner layers or walls of the bore, the same properties as 
those possessed by the outer layers of the casting.* 
With regard to the first point, trials made upon a small scale proved 
that bronze containing 6, 8, or 10 per cent of tin answered well for the 
manufacture of bronze-steel, and that the addition of zinc offered no 
advantages. Further experiments on a larger scale also showed that 
8 per cent gave the best results, and that proportion was therefore 
employed for the experimental guns ; this alloy is more readily chilled 
than that which contains 10 per cent, while over that having 6 percent 
it has the advantage of requiring less new copper when recast. 
Regarding the second point it was clear that to obtain for the walls 
of the bore or inner layers qualities similar to those of the outer layers, 
it would be neccessary to chill them also by means of a core of some 
description. Hollow cores cooled by air or water, were first tried and 
unsuccessfully, but at length a solid core of hammered copper was found 
to answer satisfactorily.f 
Having ascertained the proper alloy to use and the mode of chill 
casting to employ, the next step was to investigate the method by 
which the gun block, when cast, should be treated mechanically to ensure 
sufficient hardness and elasticity in the walls of the bore. 
From his own study of the properties of metals and from the data 
furnished by tests carried on in Austria and other countries, General 
Yon Uchatius had previously arrived at the following conclusions, viz.:— 
1. That wrought iron, steel, and the ductile metals generally, when 
they have been extended beyond their original elastic limit, and so 
undergone a permanent change of form, have the property of acquiring 
a second and higher limit of elasticity.J 
2. Also that the work usually done upon the bore of a gun when first 
fired to the detriment of accurate shooting, especially the expansion of 
the powder-chamber, should be previously performed by means of a 
* When a solid ingot was cast in an iron mould, having the thickness of the semi.diameter 
of the ingot, the interior portion of the latter was found to be composed of a greyish 
granular mass, unfit for forging. 
t The details of these various attempts are full of interest, they are given in the 
Revue d’Ajrtillerie Tome v. p. 310; and also the report of a serious accident on one occasion 
which caused the employment of water for cooling the core to be laid aside as too dangerous. 
X There is no doubt that a bar of metal strained beyond its elastic limit will if subjected 
to a greater pressure behave like a bar of an originally harder metal, for the molecules will 
have re-arranged themselves and the bar will have a higher limit of elasticity, while its 
ultimate tenacity may be increased, i.e., its ultimate strength to withstand rupture. The 
total work done to break such a bar will still, however, be about the same. This question 
will be found further discussed in Note IX, at the end of paper. 
