That is not possible in Firefox, but in case of a website like Google you will be directed automatically to the secure HTTPS version as you likely has noticed. Of course this is an extra step. There are extensions like HTTPS Everywhere can can force a secure connection, but keep in mind that you may have to create an exception if you visit a website that doesn't have a certificate installed. In such a case the server might send the certificate from the hosting company instead which causes an untrusted error message.

Ok, sad.

I already use https-everywhere. Is there an other way to request only https sites, our companies firewall denies unencrypted network traffic...