using System.Xml;
using System.IO;

//...
        {
            XmlDocument document = new XmlDocument();
            string xml = "<?xml version='1.0' encoding='UTF-8'?><Element>" +
                "<book ISBN='1-861001-57-5'><title>Pride And Prejudice</title>" +
                "<price>19.95</price></book></Element>";
            document.LoadXml(xml);
            MemoryStream ms = new MemoryStream();
            document.Save(ms);
            ms.Position = 0;
            byte[] buffer = new byte[ms.Length];
            ms.Read(buffer, 0, buffer.Length);
            ms.Close();
            ms.Dispose();
            document = null;
            Console.WriteLine(Encoding.UTF8.GetString(buffer));
        }
//...
}