Jquery Letter spacing

Jquery Letter spacing

i want to animate text with scroll down.

i apply this code.this is working. 
if scrolled = -16 
my text color id Red , but again scroll top -5 , still color is red,

Please help me. 
Thank you.

  2. $(function(){
  3.  $(window).scroll(function() {
  4.         var scrolled=-($(window).scrollTop())/50;
  5.         
  6.         $('#scrolled').text('scrolled: '+scrolled+'px'); 
  7.        if(scrolled>-10){ $('#cName').css({'letter-spacing':12+scrolled+'px'}); }
  8.        else{$('#cName').css({'color':'red'});}
  9.    });
  10.     
  11. });