title: Union with two queries returns "Call to undefined method stdClass::union()" error
body: <p>I'm currently trying to union two queries but unfortunately they return an error.</p>
  
  <pre><code>$bitfinex = DB::table('bitfinex')-&gt;select('price')-&gt;latest()-&gt;first();
  $bitstamp = DB::table('bitstamp')-&gt;select('price')-&gt;latest()-&gt;first()-&gt;union($bitfinex);
  </code></pre>
  
  <p>Returns this error:</p>
  
  <pre><code>(1/1) FatalThrowableError
  Call to undefined method stdClass::union()
  </code></pre>
  
  <p>I'd appreciate any help, thanks in advance!</p>