var speed = 55; //speed in ms
$(function(){

    $("#projects img").hide();

    timer = setInterval(function () {

        $notLoaded = $("#projects img").not(".loaded");
        $notLoaded.eq(Math.floor(Math.random() * $notLoaded.length)).fadeIn().addClass("loaded");

        if ($notLoaded.length == 0) {
            clearInterval(timer);
        }
    }, speed);

});