public void RemoveNegativeIsotopeFromFromula()
{
ChemicalFormula formulaA = new ChemicalFormula("C2H3NO");
ChemicalFormula formulaB = new ChemicalFormula("C2H5NO");
formulaA.Remove(PeriodicTable.GetElement("H")[1], -2);
Assert.AreEqual(formulaA, formulaB);
}