Newer electrolytic caps usually have a negative symbol on isulation, side of the cap. It you can't determine polarity put a 1K resistor in series with the cap. Apply a small voltage, 10-20 and notice which polarity doesn't draw current, after charging.
Norm
:I resently purchased a 330 Microfarad, 200 Volt, Radial Leads (snap-in type), Electrolytic Capacitor. The polarity of the capacitor is not readily apparent. The only feature that is different is that one lead has a crossed-hatched marking on its fastener and the other is void of marking. Your help would be appreciated.