Installing 34 bit Skype on 64 bit Xubuntu

First, install 32 bit architecture, then update:

sudo dpkg --add-architecture i386
sudo apt-get update 

Then add necessary Canonical repo and install Skype.

sudo add-apt-repository "deb http://archive.canonical.com/
$(lsb_release -sc) partner"
sudo apt-get update && sudo apt-get install skype