new_contents: import os
  import numpy as np
  import pandas as pd
  from pathlib import Path
  from openpnm.utils import logging
  logger = logging.getLogger(__name__)
  
  
  def gaseous_species_in_water(target, chemical_formula,
                               temperature="pore.temperature"):
      r"""
      Calculate Henry's law constant for gaseous species dissolved in water.
  
      Parameters
      ----------
      target : OpenPNM MultiPhase object
          Target object in which data is to be stored.
  
      chemical_formula : string
          Chemical formula of the dissolving species.
  
      temperature : string, optional
          Dictionary key containing pore temperature values.
          The default is "pore.temperature".
  
      Returns
      -------
      H : numpy ndarray
          Array containing Henry's law constant (Kpx) [atm/mol-frac]
  
      References
      ----------
      Yaws, Carl L., et al. "Solubility & Henry's Law constants for sulfur
      compounds in water: unlike traditional methods, the new correlation and
      data presented here are appropriate for very low concentrations."
      Chemical Engineering 110.8 (2003): 60-65.
  
      """
      fname = "gas_water_henry.csv"
      path = Path(os.path.realpath(__file__), "../")
      path = Path(path.resolve(), fname)
      df = pd.read_csv(path)
      row = df[df.Formula == chemical_formula]
      A, B, C, D = row.iloc[0, 3:7].astype(float)
      Tmin, Tmax = row.iloc[0, 7:9].astype(float)
      T = target[temperature]
  
      if (T.min() < Tmin) or (T.max() > Tmax):
          logger.critical("The correlation is only accurate for temperatures in the "
                          + f"range of {Tmin:.1f}K and {Tmax:.1f}K!")
  
      Hpx_log10 = A + B/T + C*np.log10(T) + D*T
      return 10**Hpx_log10
  
subject: Add partition_coefficient.py for storing partition coefficient models + basic model for gas-water system