public void AddLargeIsotopeToFormula()
{
ChemicalFormula formulaA = new ChemicalFormula("C2H3NO");
ChemicalFormula formulaB = new ChemicalFormula("C2H3NOFe");
Isotope fe = PeriodicTable.GetElement("Fe").PrincipalIsotope;
formulaA.Add(fe, 1);
Assert.AreEqual(formulaA, formulaB);
}