Humm,
"Addition of cadmium yields Ag-Cu-Zn-Cd alloys with improved fluidity and wetting and lower melting point; however cadmium is toxic. Addition of tin can play mostly the same role."
I'll bet tin is cheaper too. In any event, it's too much trouble to remove all the smoke/CO/gas detectors from the basement,
so I'll be doing lighting the torch out in the (detached) garage..
Thanks for the warning about unlabeled filler.. Hope there isn't any radioactive isotopes in there!