How to access a hashtable inside another hashtable?

[Pearls]

I have 2 hashtables:h1 and h2..
Here I require to use a hashtable within another hashtable..
Something like the following:

foreach(DictionaryEntry entry in h1)
{
/*some operation*/
  foreach(DictionaryEntry entry1 in h2)
  {
   /*processing*/
   }
}

But it results in an unexpected exception..
How can I do it??