Can anyone show me how to send cookies with httparty?

I tried sending them as part of the header in the options hash:

options = { :body => posting_string, :header => {:cookie => cookie} }

but that got me no where. The cookie looks like this:

"user=Alex+Porter; expires=Thu, 12-Aug-2010 16:48:27 GMT"

But I just peal it back to:

"user=Alex+Porter"

I'm not sure what I'm doing wrong. Can anyone set me right?