Battery seal

In a battery containing at least one chemical corrosive to glass, said battery having a terminal pin extending from within said battery, through a wall, and projecting outside said wall, and a glass seal between said pin and said wall, said seal being of the graded type wherein at least two glasses are employed, one bonded to the pin, and another to the wall and bonded, mediately or immediately, to one another, the improvement comprising said two glasses' being of sufficiently different electrical/chemical properties to produce a greater resistance to attack from said chemical than is exhibited by either of said glasses alone.