In the 1950s, when we were living and travelling (in Scotland and those other nearby countries) a snotter (some said 'snodder') was the little nub of a candle left in the holder when it was time to put in a new candle. One saves the snodders for emergencies; I have a drawerful. So the line would mean, Not only is my candle burnt out, but even the snodder's almost gone.