[jQuery] Parsing XML using jQuery

[step kapusta]

I have a problem, couldn't solve it for a long time.

I have the following XML file, returned from ajax:

<?xml version="1.0" encoding="utf-8"?>
<root>
  <buildingsList>
  <building>
    <id>1</id>
    <address>Varvarka, 1</address>
    <city_id>1</city_id>
  </building>
  <building>
    <id>2</id>
    <address>Nikolskaya, 1</address>
    <city_id>2</city_id>
  </building>
  <building>
    <id>3</id>
    <address>Varvarka, 3</address>
    <city_id>3</city_id>
   </building>
</buildingsList>
</root>

And I wanna get the value of 'city_id' element of the each element
'building'.
I do the following:

        $('/root/buildingsList/building', xml).each(function()
        {
                alert($("city_id", this).text(););
        });

But it doesn't work as I expect. Am I wrong? I'm completely tired
looking for a mistake.

I've tried the following also, but it gave the same result:

        $('building', xml).each(function()
        {
                alert($("city_id", this).text(););
        });