Window canister assembly

Claim 1

A GAS MASK CANISTER, A GAS FILTERING MATERIAL ENCLOSED THEREIN, THE WALL OF SAID CANISTER HAVING A CIRCULAR HOLE PUNCHED OUT THEREOF DEFINED BY AN INWARDLY BENT, PERIPHERAL PORTION, A SEAMLESS, METALLIC, SUBSTANTIALLY CYLINDRICAL CONTAINER OF DIAMETER SLIGHTLY SMALLER THAN THAT OF SAID HOLE, SNUGLY FITTED IN SAID HOLE, SAID CONTAINER HAVING, ON ONE SIDE, A RADIALLY OUTWARDLY FLARED, PERIPHERAL BEAD PORTION HAVING A TAPERED PORTION COMPLEMENTING AND SNUGLY SEATED IN SAID INWARDLY BENT PERIPHERAL PORTION AND BEING SOLDERED THERETO EXTERNALLY OF SAID CANISTER, SAID BEAD PORTION TERMINATING IN A RADIALLY INWARDLY BENT, ANNULAR LEDGE PORTION, THE OTHER SIDE OF SAID CONTAINER ALSO HAVING A RADIALLY INWARDLY BENT, ANNULAR LEDGE PORTION, A PAIR OF GASKETS WITHIN SAID CONTAINER, EACH GASKET BEING DIRECTLY SUPPORTED ON ONE OF SAID ANNULAR LEDGE PORTIONS, INDICATOR MEANS WITHIN SAID CONTAINER AND TIGHTLY SANDWICHED BETWEEN SAID GASKETS, SAID INDICATOR MEANS COMPRISING COMPLEMENTARY HALF DISCS POSITIONED IN THE SAME PLANE, ONE HALF DISC BEING MADE OF MATERIAL WHOSE COLOR CHANGES IN RESPONSE TO SPENDING OF SAID GAS FILTERING MATERIAL AND THE OTHER HALF DISC BEING A REFERENCE OF PERMANENT COLOR AND OF MATERIAL UNAFFECTED BY SPENDING SAID GAS FILTERING MATERIAL, AND A DISC-SHAPED WINDOW SUPPORTED BY THE GASKET ON SAID FIRST MENTIONED ANNULAR LEDGE PORTION, SAID GASKETS, AND INDICATOR MEANS BEING TIGHTLY SANDWICHED BY AND BETWEEN SAID LEDGE PORTIONS SO AS TO FORM A GAS-TIGHT SEAL, WHEREBY THE REMAINING LIFE OF SAID FILTERING MATERIAL MAY BE VISUALLY OBSERVED THROUGH SAID WINDOW BY COMPARING THE COLORS OF SAID HALF DISCS AND WHEREBY SAID CANISTER MAY BE READILY REMOVED FROM THE OUTSIDE OF SAD CANISTER BY MERELY UNSOLDERING AND WITHOUT BREAKING SAID SEAL.