diff --git a/dumux/material/binarycoefficients/fullermethod.hh b/dumux/material/binarycoefficients/fullermethod.hh
index b7895d135..decea899c 100644
--- a/dumux/material/binarycoefficients/fullermethod.hh
+++ b/dumux/material/binarycoefficients/fullermethod.hh
@@ -1,4 +1,4 @@
-// $Id: fullermethod.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/binarycoefficients/h2o_n2.hh b/dumux/material/binarycoefficients/h2o_n2.hh
index aa152aee9..682abd2a9 100644
--- a/dumux/material/binarycoefficients/h2o_n2.hh
+++ b/dumux/material/binarycoefficients/h2o_n2.hh
@@ -1,4 +1,4 @@
-// $Id: h2o_n2.hh 3783 2010-06-24 11:33:53Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/binarycoefficients/henryiapws.hh b/dumux/material/binarycoefficients/henryiapws.hh
index f0baa26e8..df4c30afd 100644
--- a/dumux/material/binarycoefficients/henryiapws.hh
+++ b/dumux/material/binarycoefficients/henryiapws.hh
@@ -1,4 +1,4 @@
-// $Id: henryiapws.hh 3783 2010-06-24 11:33:53Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/component.hh b/dumux/material/components/component.hh
index 466d3737e..9ae42e9ed 100644
--- a/dumux/material/components/component.hh
+++ b/dumux/material/components/component.hh
@@ -1,4 +1,4 @@
-// $Id: component.hh 3824 2010-07-13 13:30:02Z lauser $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
@@ -21,8 +21,6 @@
 #ifndef DUMUX_COMPONENT_HH
 #define DUMUX_COMPONENT_HH
 
-#include <dune/common/exceptions.hh>
-
 namespace Dumux
 {
 
@@ -33,6 +31,10 @@ template <class Scalar, class Implementation>
 class Component
 {
 public:
+    static void init(Scalar tempMin, Scalar tempMax, unsigned nTemp,
+            Scalar pressMin, Scalar pressMax, unsigned nPress)
+    {   Dune::dwarn << "No init routine defined - make shure that this is not necessary!" << std::endl; }
+
     /*!
      * \brief A human readable name for the compoent.
      */
diff --git a/dumux/material/components/h2.hh b/dumux/material/components/h2.hh
index c736b782e..31d707bb7 100644
--- a/dumux/material/components/h2.hh
+++ b/dumux/material/components/h2.hh
@@ -106,7 +106,7 @@ public:
     /*!
      * \brief The density [kg/m^3] of H2 at a given pressure and temperature.
      */
-    static Scalar density(Scalar temperature, Scalar pressure)
+    static Scalar gasDensity(Scalar temperature, Scalar pressure)
     {
         // Assume an ideal gas
         return IdealGas::density(molarMass(), temperature, pressure);
diff --git a/dumux/material/components/h2o.hh b/dumux/material/components/h2o.hh
index a197c7285..53dd670ad 100644
--- a/dumux/material/components/h2o.hh
+++ b/dumux/material/components/h2o.hh
@@ -1,4 +1,4 @@
-// $Id: h2o.hh 3783 2010-06-24 11:33:53Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/iapws/common.hh b/dumux/material/components/iapws/common.hh
index 659b7a59b..991cca533 100644
--- a/dumux/material/components/iapws/common.hh
+++ b/dumux/material/components/iapws/common.hh
@@ -1,4 +1,4 @@
-// $Id: common.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009-2010 by Andreas Lauser                               *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/iapws/region1.hh b/dumux/material/components/iapws/region1.hh
index 528db976f..cbcb8be2f 100644
--- a/dumux/material/components/iapws/region1.hh
+++ b/dumux/material/components/iapws/region1.hh
@@ -1,4 +1,4 @@
-// $Id: region1.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009-2010 by Andreas Lauser                               *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/iapws/region2.hh b/dumux/material/components/iapws/region2.hh
index c8fb50d44..f04599881 100644
--- a/dumux/material/components/iapws/region2.hh
+++ b/dumux/material/components/iapws/region2.hh
@@ -1,4 +1,4 @@
-// $Id: region2.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009-2010 by Andreas Lauser                               *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/iapws/region4.hh b/dumux/material/components/iapws/region4.hh
index e8c5066c5..c527846b3 100644
--- a/dumux/material/components/iapws/region4.hh
+++ b/dumux/material/components/iapws/region4.hh
@@ -1,4 +1,4 @@
-// $Id: region4.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009-2010 by Andreas Lauser                               *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/n2.hh b/dumux/material/components/n2.hh
index 1b9ad9662..c40943810 100644
--- a/dumux/material/components/n2.hh
+++ b/dumux/material/components/n2.hh
@@ -1,4 +1,4 @@
-// $Id: n2.hh 3783 2010-06-24 11:33:53Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/o2.hh b/dumux/material/components/o2.hh
index 7fa102bf5..6cef5df49 100644
--- a/dumux/material/components/o2.hh
+++ b/dumux/material/components/o2.hh
@@ -116,7 +116,7 @@ public:
      *
      * \todo density liquid oxygen
      */
-    static Scalar density(Scalar temperature, Scalar pressure)
+    static Scalar gasDensity(Scalar temperature, Scalar pressure)
     {
         // Assume an ideal gas
         return IdealGas::density(molarMass(), temperature, pressure);
diff --git a/dumux/material/components/simplednapl.hh b/dumux/material/components/simplednapl.hh
index a00a7d34f..2ec18d3b3 100644
--- a/dumux/material/components/simplednapl.hh
+++ b/dumux/material/components/simplednapl.hh
@@ -1,4 +1,4 @@
-// $Id: simplednapl.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/simpleh2o.hh b/dumux/material/components/simpleh2o.hh
index ad8fd2aa6..601b20993 100644
--- a/dumux/material/components/simpleh2o.hh
+++ b/dumux/material/components/simpleh2o.hh
@@ -1,4 +1,4 @@
-// $Id: simpleh2o.hh 3783 2010-06-24 11:33:53Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/tabulatedcomponent.hh b/dumux/material/components/tabulatedcomponent.hh
index 588cf6d14..7cf871f74 100644
--- a/dumux/material/components/tabulatedcomponent.hh
+++ b/dumux/material/components/tabulatedcomponent.hh
@@ -1,4 +1,4 @@
-// $Id: tabulatedcomponent.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/components/unit.hh b/dumux/material/components/unit.hh
index 31b3d4afb..333b290fd 100644
--- a/dumux/material/components/unit.hh
+++ b/dumux/material/components/unit.hh
@@ -1,4 +1,4 @@
-// $Id: unit.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/brookscorey.hh b/dumux/material/fluidmatrixinteractions/2p/brookscorey.hh
index 5cd1d5d53..2bf6fa2f0 100644
--- a/dumux/material/fluidmatrixinteractions/2p/brookscorey.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/brookscorey.hh
@@ -1,4 +1,4 @@
-// $Id: brookscorey.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/brookscoreyparams.hh b/dumux/material/fluidmatrixinteractions/2p/brookscoreyparams.hh
index 3bf6a5839..ae4bf6cdd 100644
--- a/dumux/material/fluidmatrixinteractions/2p/brookscoreyparams.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/brookscoreyparams.hh
@@ -1,4 +1,4 @@
-// $Id: brookscoreyparams.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/efftoabslaw.hh b/dumux/material/fluidmatrixinteractions/2p/efftoabslaw.hh
index 96f4c92eb..c8369dbed 100644
--- a/dumux/material/fluidmatrixinteractions/2p/efftoabslaw.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/efftoabslaw.hh
@@ -1,4 +1,4 @@
-// $Id: efftoabslaw.hh 3811 2010-07-05 12:59:17Z pnuske $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/efftoabslawparams.hh b/dumux/material/fluidmatrixinteractions/2p/efftoabslawparams.hh
index a1a7049e6..4ef065595 100644
--- a/dumux/material/fluidmatrixinteractions/2p/efftoabslawparams.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/efftoabslawparams.hh
@@ -1,4 +1,4 @@
-// $Id: efftoabslawparams.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/linearmaterial.hh b/dumux/material/fluidmatrixinteractions/2p/linearmaterial.hh
index f8b6dd43a..7e96ef2b3 100644
--- a/dumux/material/fluidmatrixinteractions/2p/linearmaterial.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/linearmaterial.hh
@@ -1,4 +1,4 @@
-// $Id: linearmaterial.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/linearmaterialparams.hh b/dumux/material/fluidmatrixinteractions/2p/linearmaterialparams.hh
index f3a9fe506..b0c95985a 100644
--- a/dumux/material/fluidmatrixinteractions/2p/linearmaterialparams.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/linearmaterialparams.hh
@@ -1,4 +1,4 @@
-// $Id: linearmaterialparams.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscorey.hh b/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscorey.hh
index 51d7952be..e5b4b664b 100644
--- a/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscorey.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscorey.hh
@@ -1,4 +1,4 @@
-// $Id: regularizedbrookscorey.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscoreyparams.hh b/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscoreyparams.hh
index 767a47fb0..c65b2869e 100644
--- a/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscoreyparams.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/regularizedbrookscoreyparams.hh
@@ -1,4 +1,4 @@
-// $Id: regularizedbrookscoreyparams.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchten.hh b/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchten.hh
index 072df298d..80233098b 100644
--- a/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchten.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchten.hh
@@ -1,4 +1,4 @@
-// $Id: regularizedvangenuchten.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchtenparams.hh b/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchtenparams.hh
index bbac9ad8d..c65ff9f7a 100644
--- a/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchtenparams.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/regularizedvangenuchtenparams.hh
@@ -1,4 +1,4 @@
-// $Id: regularizedvangenuchtenparams.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/vangenuchten.hh b/dumux/material/fluidmatrixinteractions/2p/vangenuchten.hh
index 45102ffe6..88603f05c 100644
--- a/dumux/material/fluidmatrixinteractions/2p/vangenuchten.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/vangenuchten.hh
@@ -1,4 +1,4 @@
-// $Id: vangenuchten.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidmatrixinteractions/2p/vangenuchtenparams.hh b/dumux/material/fluidmatrixinteractions/2p/vangenuchtenparams.hh
index 25181813b..0812da791 100644
--- a/dumux/material/fluidmatrixinteractions/2p/vangenuchtenparams.hh
+++ b/dumux/material/fluidmatrixinteractions/2p/vangenuchtenparams.hh
@@ -1,4 +1,4 @@
-// $Id: vangenuchtenparams.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2008 by Andreas Lauser, Bernd Flemisch                    *
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidstate.hh b/dumux/material/fluidstate.hh
index e496438f9..1d9dc2599 100644
--- a/dumux/material/fluidstate.hh
+++ b/dumux/material/fluidstate.hh
@@ -1,4 +1,4 @@
-// $Id: fluidstate.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
@@ -117,8 +117,8 @@ public:
      *
      * Unit: [Pa] = [N/m^2]
      */
-    Scalar partialPressure(int componentIdx) const
-    { DUNE_THROW(Dune::NotImplemented, "FluidState::partialPressure()"); }
+    Scalar fugacity(int componentIdx) const
+    { DUNE_THROW(Dune::NotImplemented, "FluidState::fugacity()"); }
 
     /*!
      * \brief Return the total pressure of the gas phase.
diff --git a/dumux/material/fluidsystems/2p_system.hh b/dumux/material/fluidsystems/2p_system.hh
index e1dab713b..eea985f1e 100644
--- a/dumux/material/fluidsystems/2p_system.hh
+++ b/dumux/material/fluidsystems/2p_system.hh
@@ -1,4 +1,4 @@
-// $Id: 2p_system.hh 3784 2010-06-24 13:43:57Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/fluidsystems/h2o_n2_system.hh b/dumux/material/fluidsystems/h2o_n2_system.hh
index a4154846c..f1eb18b80 100644
--- a/dumux/material/fluidsystems/h2o_n2_system.hh
+++ b/dumux/material/fluidsystems/h2o_n2_system.hh
@@ -1,4 +1,4 @@
-// $Id: h2o_n2_system.hh 3824 2010-07-13 13:30:02Z lauser $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
@@ -91,57 +91,6 @@ public:
         DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
     }
 
-    /*!
-     * \brief Given the gas phase's composition, temperature and
-     *        pressure, compute the partial presures of all components
-     *        in [Pa] and assign it to the FluidState.
-     *
-     * This is required for models which cannot calculate the the
-     * partial pressures of the components in the gas phase from the
-     * degasPressure(). To use this method, the FluidState must have a
-     * setPartialPressure(componentIndex, pressure) method.
-     */
-    template <class FluidState>
-    static void computePartialPressures(Scalar temperature,
-                                        Scalar pg,
-                                        FluidState &fluidState)
-    {
-        Scalar X1 = fluidState.massFrac(gPhaseIdx, H2OIdx);
-
-        // We use the newton method for this. For the initial value we
-        // assume all components to be an ideal gas
-        Scalar pH2O = fluidState.moleFrac(gPhaseIdx, H2OIdx) * pg;
-        Scalar eps = pg*1e-9;
-
-        Scalar deltaP = pH2O;
-        Valgrind::CheckDefined(pH2O);
-        Valgrind::CheckDefined(deltaP);
-        for (int i = 0; i < 5 && std::abs(deltaP/pg) > 1e-9; ++i) {
-            Scalar f =
-                H2O::gasDensity(temperature, pH2O)*(X1 - 1) +
-                X1*N2::gasDensity(temperature, pg - pH2O);
-
-            Scalar df_dp;
-            df_dp  =
-                H2O::gasDensity(temperature, pH2O + eps)*(X1 - 1) +
-                X1*N2::gasDensity(temperature, pg - (pH2O + eps));
-            df_dp -=
-                H2O::gasDensity(temperature, pH2O - eps)*(X1 - 1) +
-                X1*N2::gasDensity(temperature, pg - (pH2O - eps));
-            df_dp /=
-                2*eps;
-
-            deltaP = - f/df_dp;
-
-            pH2O += deltaP;
-            Valgrind::CheckDefined(pH2O);
-            Valgrind::CheckDefined(deltaP);
-        }
-
-        fluidState.setPartialPressure(H2OIdx, pH2O);
-        fluidState.setPartialPressure(N2Idx, pg - pH2O);
-    };
-
     /*!
      * \brief Given a phase's composition, temperature, pressure, and
      *        the partial pressures of all components, return its
@@ -153,16 +102,26 @@ public:
                                Scalar pressure,
                                const FluidState &fluidState)
     {
-        if (phaseIdx == lPhaseIdx)
-            return liquidPhaseDensity_(temperature,
-                                       pressure,
-                                       fluidState.moleFrac(lPhaseIdx, H2OIdx),
-                                       fluidState.moleFrac(lPhaseIdx, N2Idx));
-        else if (phaseIdx == gPhaseIdx)
-            return gasPhaseDensity_(temperature,
-                                    pressure,
-                                    fluidState.moleFrac(gPhaseIdx, H2OIdx),
-                                    fluidState.moleFrac(gPhaseIdx, N2Idx));
+        if (phaseIdx == lPhaseIdx) {
+            // See: Ochs 2008
+            // \todo: proper citation
+            Scalar rholH2O = H2O::liquidDensity(temperature, pressure);
+            Scalar clH2O = rholH2O/H2O::molarMass();
+        
+            // this assumes each nitrogen molecule displaces exactly one
+            // water molecule in the liquid
+            return
+                clH2O*(H2O::molarMass()*fluidState.moleFrac(lPhaseIdx, H2OIdx)
+                       +
+                       N2::molarMass()*fluidState.moleFrac(lPhaseIdx, N2Idx));
+        }
+        else if (phaseIdx == gPhaseIdx) {
+            Scalar fugH2O = fluidState.fugacity(H2OIdx);
+            Scalar fugN2 = fluidState.fugacity(N2Idx);
+            return 
+                H2O::gasDensity(temperature, fugH2O) +
+                N2::gasDensity(temperature, fugN2);
+        }
         DUNE_THROW(Dune::InvalidStateException, "Invalid phase index " << phaseIdx);
     }
 
@@ -337,23 +296,46 @@ public:
     }
 
     /*!
-     * \brief Returns the fugacity coefficient of a component in a
+     * \brief Returns the activity coefficient of a component in a
      *        phase.
      *
-     * For solutions with only traces in a solvent this boils down to
-     * the inverse Henry constant for the solutes and the partial
-     * pressure for the solvent.
+     * We define the activity coefficent \f$\gamma_{\alpha,\kappa}\f$
+     * of component \f$\kappa\f$ by the following equation:
+     *  \f[ f_\kappa = p_\alpha \gamma_{\alpha,\kappa} \f]
+     * where \f$f_\kappa\f$  is the component's fugacity and \f$p_\alpha\f$
+     * is the phase' pressure
+     *
+     * For liquids with very low miscibility this boils down to the
+     * inverse Henry constant for the solutes and the partial pressure
+     * for the solvent.
+     *
+     * For ideal gases this is equivalent to the gas pressure, in real
+     * gases it is the gas pressure times the component's fugacity
+     * coefficient.
      */
     template <class FluidState>
-    static Scalar fugacityCoeff(int phaseIdx,
+    static Scalar activityCoeff(int phaseIdx,
                                 int compIdx,
                                 Scalar temperature,
                                 Scalar pressure,
                                 const FluidState &state)
     {
-        if (phaseIdx != lPhaseIdx)
-            DUNE_THROW(Dune::NotImplemented,
-                       "Fugacities in the gas phase");
+        if (phaseIdx == gPhaseIdx) {
+            return pressure;
+            Scalar fugH2O = std::max(1e-3, state.fugacity(H2OIdx));
+            Scalar fugN2 = std::max(1e-3, state.fugacity(N2Idx));
+            Scalar cH2O = H2O::gasDensity(temperature, fugH2O) / H2O::molarMass();
+            Scalar cN2 = N2::gasDensity(temperature, fugN2) / N2::molarMass();
+            
+            Scalar alpha = (fugH2O + fugN2)/pressure;
+
+            if (compIdx == H2OIdx)
+                return fugH2O/(alpha*cH2O/(cH2O + cN2));
+            else if (compIdx == N2Idx)
+                return fugN2/(alpha*cN2/(cH2O + cN2));
+            
+            DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
+        }
 
         switch (compIdx) {
         case H2OIdx: return H2O::vaporPressure(temperature);
@@ -362,59 +344,6 @@ public:
         DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
     }
 
-    /*!
-     * \brief Given a component's pressure and temperature, return its
-     *        density in a phase [kg/m^3].
-     */
-    static Scalar componentDensity(int phaseIdx,
-                                   int compIdx,
-                                   Scalar temperature,
-                                   Scalar pressure)
-    {
-        if (phaseIdx == lPhaseIdx) {
-            if (compIdx == H2OIdx)
-                return H2O::liquidDensity(temperature, pressure);
-            else if (compIdx == N2Idx)
-                return N2::liquidDensity(temperature, pressure);
-            DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
-        }
-        else if (phaseIdx == gPhaseIdx) {
-            if (compIdx == H2OIdx) {
-                return H2O::gasDensity(temperature, pressure);
-            }
-            else if (compIdx == N2Idx)
-                return N2::gasDensity(temperature, pressure);
-            DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
-        }
-        DUNE_THROW(Dune::InvalidStateException, "Invalid phase index " << phaseIdx);
-    };
-
-    /*!
-     * \brief Given a component's density and temperature, return the
-     *        corresponding pressure in a phase [Pa].
-     */
-    static Scalar componentPressure(int phaseIdx,
-                                    int compIdx,
-                                    Scalar temperature,
-                                    Scalar density)
-    {
-        if (phaseIdx == lPhaseIdx) {
-            if (compIdx == H2OIdx)
-                return H2O::liquidPressure(temperature, density);
-            else if (compIdx == N2Idx)
-                return N2::liquidPressure(temperature, density);
-            DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
-        }
-        else if (phaseIdx == gPhaseIdx) {
-            if (compIdx == H2OIdx)
-                return H2O::gasPressure(temperature, density);
-            else if (compIdx == N2Idx)
-                return N2::gasPressure(temperature, density);
-            DUNE_THROW(Dune::InvalidStateException, "Invalid component index " << compIdx);
-        }
-        DUNE_THROW(Dune::InvalidStateException, "Invalid phase index " << phaseIdx);
-    };
-
     /*!
      * \brief Given a phase's composition, temperature and pressure,
      *        return the binary diffusion coefficent for components
@@ -496,8 +425,8 @@ public:
                 N2::gasEnthalpy(temperature, pN2);
         }
         else {
-            Scalar pWater = fluidState.partialPressure(H2OIdx);
-            Scalar pN2 = fluidState.partialPressure(N2Idx);
+            Scalar pWater = fluidState.fugacity(H2OIdx);
+            Scalar pN2 = fluidState.fugacity(N2Idx);
 
             Scalar result = 0;
             result +=
@@ -533,7 +462,7 @@ private:
         // \todo: proper citation
         Scalar rholH2O = H2O::liquidDensity(T, pl);
         Scalar clH2O = rholH2O/H2O::molarMass();
-
+        
         // this assumes each nitrogen molecule displaces exactly one
         // water molecule in the liquid
         return
@@ -542,69 +471,10 @@ private:
                    xlN2*N2::molarMass());
     }
 
-    // defect of gas density
-    static inline Scalar gasDefect_(Scalar pH2O, Scalar T, Scalar pg, Scalar xgH2O, Scalar xgN2)
-    {
-        // this assumes that sum of the fugacities of the individual
-        // components add up to the gas pressure
-        return
-            H2O::gasDensity(T, pH2O)/H2O::molarMass()*(xgH2O - 1) +
-            xgH2O*N2::gasDensity(T, pg - pH2O)/N2::molarMass();
-    }
-
     static Scalar gasPhaseDensity_(Scalar T, Scalar pg, Scalar xgH2O, Scalar xgN2)
     {
-        // assume ideal gas for the initial condition
-        Scalar pH2O = pg*xgH2O;
-        Scalar delta = 1e100;
-
-        // newton method. makes sure that the total pressure of the
-        // gas phase is the sum of the individual gas phase fugacities
-        // of the individual components
-        for (int i = 0; i < 10; ++i) {
-            Scalar f;
-            Scalar df_dpH2O;
-
-            f = gasDefect_(pH2O, T, pg, xgH2O, xgN2);
-            Scalar eps = (std::abs(pg) + 1)*1e-9;
-            df_dpH2O = gasDefect_(pH2O + eps, T, pg, xgH2O, xgN2);
-            df_dpH2O -= gasDefect_(pH2O - eps, T, pg, xgH2O, xgN2);
-            df_dpH2O /= 2*eps;
-
-            delta = - f/df_dpH2O;
-            pH2O += delta;
-
-            if (std::abs(delta) < 1e-10*pg) {
-                return H2O::gasDensity(T, pH2O) + N2::gasDensity(T, pg - pH2O);
-            }
-        };
-        DUNE_THROW(NumericalProblem,
-                   "Can not calculate the gas density at "
-                   << " T=" << T
-                   << " pg=" << pg
-                   << " xgH2O=" << xgH2O
-                   << " xgN2=" << xgN2
-                   << "\n");
+        return H2O::gasDensity(T, pg*xgH2O) + N2::gasDensity(T, pg*xgN2);
     };
-
-    template <class FluidState>
-    static void checkConsistentGasDensity_(Scalar rhoToTest,
-                                           Scalar pg,
-                                           const FluidState &fluidState)
-    {
-#ifndef NDEBUG
-        Scalar rho = gasPhaseDensity_(fluidState.temperature(),
-                                      pg,
-                                      fluidState.moleFrac(gPhaseIdx, H2OIdx),
-                                      fluidState.moleFrac(gPhaseIdx, N2Idx));
-        static const Scalar eps = 1e-8;
-        if (std::abs(rhoToTest/rho - 1.0) > eps) {
-            DUNE_THROW(Dune::InvalidStateException,
-                       "Density of gas phase is inconsistent: rho1/rho2 = "
-                       << rhoToTest/rho);
-        }
-#endif
-    }
 };
 
 } // end namepace
diff --git a/dumux/material/idealgas.hh b/dumux/material/idealgas.hh
index 9bc012277..5592c17b5 100644
--- a/dumux/material/idealgas.hh
+++ b/dumux/material/idealgas.hh
@@ -1,4 +1,4 @@
-// $Id: idealgas.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2009 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/settablephase.hh b/dumux/material/settablephase.hh
index 29320b578..621ce608c 100644
--- a/dumux/material/settablephase.hh
+++ b/dumux/material/settablephase.hh
@@ -1,4 +1,4 @@
-// $Id: settablephase.hh 3777 2010-06-24 06:46:46Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2010 by Andreas Lauser
  *   Institute of Hydraulic Engineering                                      *
diff --git a/dumux/material/spatialparameters/boxspatialparameters.hh b/dumux/material/spatialparameters/boxspatialparameters.hh
index f15cdd6b3..3a1a4b97b 100644
--- a/dumux/material/spatialparameters/boxspatialparameters.hh
+++ b/dumux/material/spatialparameters/boxspatialparameters.hh
@@ -1,4 +1,4 @@
-// $Id: boxspatialparameters.hh 3783 2010-06-24 11:33:53Z bernd $
+// $Id$
 /*****************************************************************************
  *   Copyright (C) 2010 by Andreas Lauser                                    *
  *   Institute of Hydraulic Engineering                                      *
@@ -39,10 +39,14 @@ class BoxSpatialParameters
 {
     typedef typename GET_PROP_TYPE(TypeTag, PTAG(Scalar)) Scalar;
     typedef typename GET_PROP_TYPE(TypeTag, PTAG(GridView)) GridView;
+    typedef typename GET_PROP_TYPE(TypeTag, PTAG(SpatialParameters)) Implementation;
 
     enum {
         dimWorld = GridView::dimensionworld
     };
+    
+    typedef typename GridView::template Codim<0>::Entity Element;
+    typedef typename GET_PROP_TYPE(TypeTag, PTAG(FVElementGeometry)) FVElementGeometry;
 
     typedef typename GridView::ctype CoordScalar;
     typedef Dune::FieldMatrix<CoordScalar, dimWorld, dimWorld> Tensor;
@@ -54,6 +58,41 @@ public:
     ~BoxSpatialParameters()
     {}
 
+    /*!
+     * \brief Returns the factor by which the volume of a sub control
+     *        volume needs to be multiplied in order to get cubic
+     *        meters.
+     *
+     * By default that's just 1.0
+     */
+    Scalar extrusionFactorScv(const Element &element,
+                              const FVElementGeometry &fvElemGeom,
+                              int scvIdx) const
+    { return 1.0; }
+
+    /*!
+     * \brief Returns the factor by which the area of a sub control
+     *        volume face needs to be multiplied in order to get
+     *        square meters.
+     *
+     * By default it is the arithmetic mean of the extrusion factor of
+     * the face's two sub-control volumes.
+     */
+    Scalar extrusionFactorScvf(const Element &element,
+                              const FVElementGeometry &fvElemGeom,
+                              int scvfIdx) const
+    { 
+        return
+            0.5 *
+            (asImp_().extrusionFactorScv(element, 
+                                         fvElemGeom, 
+                                         fvElemGeom.subContVolFace[scvfIdx].i)
+             +
+             asImp_().extrusionFactorScv(element, 
+                                         fvElemGeom, 
+                                         fvElemGeom.subContVolFace[scvfIdx].j));
+    }
+
     /*!
      * \brief Averages the intrinsic permeability.
      */
@@ -82,6 +121,13 @@ public:
             for (int j = 0; j < dimWorld; ++j)
                 result[i][j] = harmonicMean(K1[i][j], K2[i][j]);
     }
+
+protected:
+    Implementation &asImp_()
+    { return *static_cast<Implementation*>(this); }
+    
+    const Implementation &asImp_() const
+    { return *static_cast<const Implementation*>(this); }
 };
 
 } // namespace Dumux