C#

static void ProcessNode
{
    //Other node type processed [correctly] before and after this method....
    if (reader.NodeType == XmlNodeType.Text)
    {
        string source = SecurityElement.Escape(reader.Value);
        writer.WriteRaw(source);
        return; 
    }     
}

static void ProcessFile(XmlTextReader reader)
{
    reader.Read(); // Read the first element to get encoding
    using (XmlTextWriter writer = new XmlTextWriter(destinationPath, reader.Encoding))
    {
        Process(reader, writer); //Process the first element
        while (reader.Read()) //Now process all remaining elements
        {
            ProcessNode(reader, writer);
        }
    }
}

static void Main(string[] args)
{
    using (XmlTextReader myReader = new XmlTextReader(sourcePath))
    {
        ProcessFile(myReader);
    }
}