Invisible ink

 Early Indian security agency was facing problem of leaking secret ideas or plans, terrorist and anti-national were took benefit of that information. Right now Indian security agency is  very advance, they have some devices which help them to safe all secret think and notes form others. One device is invisible ink, it is very helpful for security agency, because whatever they write by that, they can see by a special glass, without special glass pages looking like blank. Now they are using this device without any fears.