sentences:  One manifold is connected to a source of purified inert gas, while the other is connected to a vacuum pump.The inert-gas line is vented through an oil bubbler, while solvent vapors and gaseous reaction products are prevented from contaminating the vacuum pump by a liquid-nitrogen or dry-ice/acetone cold trap.Special stopcocks or Teflon taps allow vacuum or inert gas to be selected without the need for placing the sample on a separate line.