No abstract

Magnetic, Mössbauer effect, and thermal properties have been evaluated for specimens of the mineral ankerite and are contrasted with similar measurements reported for the mineral siderite to determine if ankerite (and ferroan dolomite), like siderite, may be important in paleomagnetism as a producer of secondary, spurious remanent moments as the result of oxidation in air. Our data indicate that ankerite and siderite both have comparable thermal stabilities and that ankerite does break down to form iron oxides at temperatures as low as 250°C during thermal demagnetization. We conclude from our data that any iron carbonate, siderite, ankerite, or ferroan dolomite, may readily oxidize in air to maghemite or hematite thus producing a spurious remanent moment (RM) that can dominate the magnetic properties of the specimen. Thermal demagnetization of ankerite or siderite at lower temperatures (below 250°C) does not appear to produce such a spurious RM. As might be expected, the quantity of secondary iron oxides produced by oxidation is limited by the iron content in the carbonate crystal lattice. Oxidized siderite produces significantly greater amounts of iron oxides than equivalent percentages of ankerite, which in turn produces more iron oxides than equal amounts of ferroan dolomite in a given sample.

During the past 20 years, the U.S. Navy has undertaken an extensive evaluation of water mist for fire protection applications aboard ship. Both small and full‐scale tests have been conducted to study water mist as a replacement for Halon 1301 and to explore the possible use of mist in lieu of conventional sprinklers. Tests have been conducted at the David Taylor Ship Research and Development Center in Annapolis, Maryland, at the Naval Research Laboratory, Chesapeake Division, and aboard the Navy'S fire research vessel, the Ex‐Shadwell in Mobile, Alabama. Engineering analysis and trade‐off studies have been conducted to compare ship impact (cost, space and weight) of water mist versus Halon and other gaseous alternatives. As a result of the testing and analysis completed thus far, the Navy has specified water mist to protect the propulsion machinery spaces on the Navy'S next new ship, the USS San Antonio (LPD‐17), currently undergoing final design at Avondale Industries.

No abstract