$(function() { 
// set opacity to nill on page load 
$("ul#menu span").css("opacity","0"); 
// on mouse over 
$("ul#menu span").hover(function () { 
// animate opacity to full 
$(this).stop().animate({ 
opacity: 1 
}, 'slow'); 
}, 
// on mouse out 
function () { 
// animate opacity to nill 
$(this).stop().animate({ 
opacity: 0 
}, 'slow'); 
}); 
});