function getHenrys(queryChemical,tempC,object2)
{
  //estimate the henry's constant from the
  //chemical name, temperature
  //get the molecular weight, vapor pressure and solubility from the xml data set
  //object is the xml Applet object passed from the HTML page

  queryVP = queryChemical + "/VaporPressure[@Temp='" + tempC + "']";
  querySO = queryChemical + "/Solubility[@Temp='" + tempC + "']";
  queryMW = queryChemical + "/MW" 

 
  VP = getXMLData(queryVP,object2);
  SO = getXMLData(querySO,object2);
  MW = getXMLData(queryMW,object2);

  //convert the vapor pressure result to atm
  VP = Math.pow(10,VP);

  //to convert units to atm m3/mol:  
  //VP in atm
  //SO in mg/L
  //MW in g/mol
  //   HC  =  VP/( SO/MW )
  //  ATM m3/mol =    atm/ (  (mg/L) (1000 L/m3) (g/1000 mg) (mol/g)  )
  // (numerically the 1000s cancel out)  
  HC = VP/(SO/MW);

  return HC;
}