Oxygen sensing polarographic cell

Claim 1

IN COMBINATIN: A COVER OF INVERTED CUP SHAPE HAVING A CENTRAL APERTURE; A BASE PLATE; MEANS SEALINGLY FASTENING SAID BASE PLATE TO SAID COVER; A HOLLOW FIRST ELECTRODE OF LARGE SURFACE AREA; MEANS RESILIENTLY SUPPORTING SAID ELECTRODE ON SAID BASE PLATE WITHIN SAID COVER; A CAP MEMBER OF INSULATING MATERIAL SUPPORTED ON SAID ELECTRODE AND HAVING A CENTRL BORE ALIGNED WITH SAID APERTURE; AN ELECTRICALLY CONDUCINT ANNULUS HAVING A CONICAL ELECTRODE-ENGAGING SURFACE ON SAID CAP MEMBER SURROUNDING SAID BORE; A FLEXIBLE CLOSURE MEMBER ON SAID CAP MEMBER INCLUDING A FINELY APERTURED INNER LAYER OF MATERIAL CAPABLE OF ACTING AS A SECOND ELECTRODE AND OF VERY MUCH SMALLER AREA THAN SAID FIRST ELECTRODE, AND AN OUTER LAYER SELECTIVELY PERMEABLE BY OXYGEN BUT SUBSTANTIALLY IMPERMEABLE BY AN ELECTROLYTE; A RESILIENT SEALING RING BETWEEN SAID COVER AND SAID CAP MEMBER PRESSING SAID CLOSURE MEMBER AGAINST SAID SURFACE TO CLOSE BOTH SAID APERTURE AND SAID BORE, AND TO INSURE ELECTRICAL CONNECTION