ON THE CHEMICAL NATURE OF ALLOYS. 37 
Report on the Chemical Nature of Alloys. By A. Mattutsssen, F.R.S., 
Lecturer on Chemistry in St. Mary’s Hospital. 
Ovr knowledge of this subject is at present very limited; and, as far as we 
can ascertain, a liquid alloy of two metals may be either 
1. A solution of one metal in another, or 
2. A chemical combination, or 
3. A mechanical mixture, or 
4, A solution or mixture of two or all of the above. 
On the contrary, an alloy in the solid state may be either 
1. A solidified solution of one metal in the other, or 
2. A chemical combination, or 
3. A mechanical mixture, or ; 
4. A solidified solution or mechanical mixture of two or all of the above. 
Under the term solution of one metal in another, I understand one like that 
of ether and alcohol; for these two liquids may be mixed in any proportion, 
and they will not separate, by standing, into two layers. Oil and water, on the 
contrary, when shaken up well together, present for a moment a homogeneous 
mass, and as such may be considered a mechanical mixture of the two. The 
case of mixing ether and water together is somewhat different; for ether 
dissolves a certain amount of water, and water a certain amount of ether: when 
these liquids, say in equal parts, are shaken well together, then, as with oil 
and water, for a time a homogeneous mass will exist ; such a one, however, is 
not a mechanical mixture of ether and water, but a mechanical mixture of a 
solution of ether in water and of water in ether. Again, when sulphuric 
acid is added to a large quantity of water, the solution is not a simple 
one of sulphuric acid in water, but a solution of a chemical combination of 
sulphuric acid and water in water. 
Under the term solidified solution, I understand a most intimate mixture, 
such as would occur in the sudden conversion of a solution into a solid, and a 
much more intimate mixture than can be obtained by ordinary mechanical 
means—in fact a perfectly homogeneous diffusion of one body in another. An 
excellent example of a homogeneous diffusion is furnished by glass, which is 
formed in the liquid state at a high temperature, and solidifies on cooling 
without separation of the different silicates. But how are we to find out 
what an alloy is? Chemistry only affords us means (by analysis) by which 
we are enabled to determine whether an alloy is a homogeneous mass or not, 
thereby indicating the presence or absence of mechanical mixtures. 
This is not enough for us to determine the chemical nature of alloys; we 
must therefore look elsewhere and see whether we cannot gain information 
on the subject ; and in doing so we shall find that the study of their physical 
properties offers a means whereby the chemical nature of an alloy may be 
ascertained. 
The physical properties may be divided into two classes— 
I. Those which do not indicate the chemical nature of the alloy. 
Il. Those which do indicate the chemical nature of the alloy. 
To the first belong, for instance— 
1. Specific Gravity —On comparing those observed with those calculated, 
very little difference will be found between the values ; take as example those 
of the bismuth-lead alloys, and those of the metals tin and gold*, 
* Phil. Trans. 1860, p. 177. 
