function alter_float(body_tag) {
 
   var bodyId = document.getElementById(body_tag);    // ID of the BODY tag
     var images = document.getElementById(body_tag).getElementsByTagName("img");
		/*myWindow=window.open('','MyName','width=200,height=100');*/		
		var dir ="right"
		for (var img_index = 0; img_index <images.length;img_index++){			
			images[img_index].setAttribute("style", "float: "+dir +";");
			if (dir == "left") dir = "right";
			else dir = "left";
			/*myWindow.document.write(images[img_index].src, images[img_index].style.float+"<br/>");*/
		}
}