232 Mr. JIallet on the Physical Conditions 



atoms of copper to I'OO atom of tin, which would give rise to the rational for- 

 mula — 



58 (Cun + Sn) + (Cu3 + Sii) + (Cu^ + Sn) + Siijo- 



There is, therefore, a large proportion of uncombined tin merely diffused 

 through the mass (like water in a' sponge), and the whole combination is held 

 together, independently of this, in the very loose way that characterizes the 

 alloys of all metals, in which the combining proportions demand large multipliers 

 for the atoms of either or both metals ; the general fact admitting of no exception, 

 that the simplest and most elementary alloys, are those most firmly combined. 



172. An extensive series of experiments made some years since by the 

 author, upon the effects of additions in minute but atomic proportions, of various 

 third metals to the binary alloy of copper and zinc, known as Muntz's metal 

 (No. 10, Table x.) embracing antimony, lead, iron, bismuth, arsenic, and silver, 

 proved that in every instance the ductility, tenacity, flexibility, and resistance 

 to torsion were seriously impaired by proportions under even 1 per cent. 

 These experiments were conducted upon a large scale, merchant sheathing 

 sheets being rolled out from the alloy in each instance ; they are, therefore, to 

 be relied upon, and may probably be applied with like confidence to the binary 

 alloys of copper and tin also, as indicating like results. 



173. If it should appear that part of the tin of gun-metals separates solely in 

 virtue of its greater fusibility and less specific gravity, and in every atomic 

 constitution, the fact would seem to make vain any chemical consideration as 

 to the proportions of these alloys, and make it doubtful that they were true 

 chemical compounds at all; but though often loosely so stated, the fact seems 

 in no instance ascertained to be so, and the specific gravities of the alloys, 

 differing from the mean of their constituents, as well as all other facts, oppose 

 the conclusion that such mere mechanical segregation of the tin alone, ever 

 occurs with atomically proportioned alloys. Lamartilliere (" Eesearches sur 

 r Ar tiller ie") mentions uncombined nodules of tin,, as occasionally found segre- 

 gated, and embedded in the interior of the mass of bronze guns. Nevertheless, 

 it is extremely doubtful, that either tin or copper is ever segregated in a state 

 of purity, i. e. unalloyed with each other, from any primary alloy between 

 100 : 9 and 100 : 12 by weight. 



