Strange Chemical Formula

[Nim]

I don't get this:

"Its empirical formula is
C 10 H 17 N 3 S • 2 HCl • H 2 O"

What is with those dots? And the middle part has a number before a letter...

[Monique]

Well, it means you have got a mixture of molecules.

C_{10}H_{17}N_3S with two molecules of HCl and a single molecule of H_2O