Low Melting Point Alloys

30-30 chamber casting (top) and 30-30 shell (bottom).

I gave Jack a hand casting an impression of the firing chamber of his Martini-Henry rifle. He used Wood's Metal, an alloy with a really low melting point. Boiling water will melt it. It has another interesting property in that it doesn't shrink when it cools, so you can cast an impression of something and your casting will have exactly the same dimensions as the object you copied. You can understand how that would be important in a project like this.
    I got a little curious about this material so I did a little reading and found there are a whole bunch of different metallic mixtures that have relatively low melting points. Wikipedia has a chart. Reading over this chart it appears that only a handful of elements are used in any of these alloys. Well, this is just crying out for further analysis, so I transport their data into my own spreadsheet and mung it around, and presto, we have a new table. Not sure whether it tells us anything significant, but at least the similarities and differences between the various alloys can be easily seen.