diff --git a/geopandas/geodataframe.py b/geopandas/geodataframe.py
index 08f7286..4c74bac 100644
--- a/geopandas/geodataframe.py
+++ b/geopandas/geodataframe.py
@@ -253,8 +253,8 @@ class GeoDataFrame(GeoPandasBase, DataFrame):
                 'id': str(i),
                 'type': 'Feature',
                 'properties':
-                    dict((k, v) for k, v in iteritems(row) if k != 'geometry'),
-                'geometry': mapping(row['geometry']) }
+                    dict((k, v) for k, v in iteritems(row) if k != self._geometry_column_name),
+                'geometry': mapping(row[self._geometry_column_name]) }
 
         return json.dumps(
             {'type': 'FeatureCollection',
diff --git a/geopandas/geoseries.py b/geopandas/geoseries.py
index 077a9cb..34410eb 100644
--- a/geopandas/geoseries.py
+++ b/geopandas/geoseries.py
@@ -113,9 +113,6 @@ class GeoSeries(GeoPandasBase, Series):
     def __getitem__(self, key):
         return self._wrapped_pandas_method('__getitem__', key)
 
-    def __getslice__(self, i, j):
-        return self._wrapped_pandas_method('__getslice__', i, j)
-
     def order(self, *args, **kwargs):
         return self._wrapped_pandas_method('order', *args, **kwargs)
 
diff --git a/geopandas/io/sql.py b/geopandas/io/sql.py
index b70d774..8c75fab 100644
--- a/geopandas/io/sql.py
+++ b/geopandas/io/sql.py
@@ -28,7 +28,8 @@ def read_postgis(sql, con, geom_col='geom', crs=None, index_col=None,
     index_col, coerce_float, params
 
     """
-    df = read_sql(sql, con, index_col, coerce_float, params)
+    df = read_sql(sql, con, index_col=index_col, coerce_float=coerce_float, 
+                  params=params)
     if geom_col not in df:
         raise ValueError("Query missing geometry column '{}'".format(
             geom_col))
diff --git a/tests/test_geodataframe.py b/tests/test_geodataframe.py
index 32dbf8b..2d5f60f 100644
--- a/tests/test_geodataframe.py
+++ b/tests/test_geodataframe.py
@@ -188,6 +188,17 @@ class TestDataFrame(unittest.TestCase):
         self.assertTrue(data['type'] == 'FeatureCollection')
         self.assertTrue(len(data['features']) == 5)
 
+    def test_to_json_geom_col(self):
+        df = self.df.copy()
+        df['geom'] = df['geometry']
+        df['geometry'] = np.arange(len(df))
+        df.set_geometry('geom', inplace=True)
+
+        text = df.to_json()
+        data = json.loads(text)
+        self.assertTrue(data['type'] == 'FeatureCollection')
+        self.assertTrue(len(data['features']) == 5)
+
     def test_to_json_na(self):
         # Set a value as nan and make sure it's written
         self.df['Shape_Area'][self.df['BoroName']=='Queens'] = np.nan