hermetically

adv. 1. In an hermetical manner; chemically. Boyle. [ 1913 Webster ]

2. By fusion, so as to form an air-tight closure. [ 1913 Webster ]

☞ A vessel or tube is hermetically sealed when it is closed completely against the passage of air or other fluid by fusing the extremity; -- sometimes less properly applied to any air-tight closure. [ 1913 Webster ]