JQuery Creating Webkit CSS Properties

JQuery Creating Webkit CSS Properties

I am trying to create a series of gradient masked images from the same source. Using css transitions, I was going to have them systematically fade at different times...The problem is, I'm having problems with quotes and string literals.

for (i=1; i<24; i++){

                                var maskstring = "-webkit-gradient(linear, left top, right bottom, 
color-stop(0.00,  rgba(0,0,0,1)),
color-stop(1.00,  rgba(0,0,0,0)))";
  var src = 'images/mts.jpg';
var divid = "mydiv" + i;

$('#' + divid).css({
  '-webkit-mask-position':'' + i*10 + ' ' + i*10,
  '-webkit-mask-size':'30px 30px',
  '-webkit-mask-repeat':'no-repeat',
  '-webkit-mask-image': maskstring;
}).append("<div><img src='images/mts.jpg'></div>");
}

I'm getting a syntax error when trying to add the maskstring. I imagine I have to break it up in someway so that all the properties are recognized and it's not just all one long string. Does anyone have a recommendation on how to format it differently?