I recently came across this 18 size swing out case housing a very nice Marked 940 Hamilton.

Can anyone identify the case metal composition?

Thanks
Rick

That is a Swiss casemaker est. ~ 1906 registration data;

Central Watch Case Co. (im Rechteck) Gehäuse; Biel, Schweiz; registriert am 4.9.1906 Fabrique de Boites La Centrale SA Gehäuse; Biel, Schweiz; registriert am 4.9.1906
Central Watch Case Co. (im Rechteck) Gehäuse; Biel, Schweiz; registriert am 25.5.1945 Fabrique de Boites La Centrale SA Gehäuse; Biel, Schweiz; registriert am 25.5.1945
Central Watch Case Co. Swiss La Centrale SA Gehäuse; Biel, Schweiz; registriert am

Probably sold to Canadian market and original to that watch. My honest "Guess" is Nickel or Base Metal.

Hi David, thanks very much. That fits pretty well, the watch dates to circa 1905.

Regards
Rick