Abstract: This invention concerns improvements in the performance of a mobile gravity gradient instrument (GGI). Gravity gradiometers measure one or more components of the gradient of gravity which is expressed as the gradient of a gravity vector, or in other words a tensor. The instrument comprises a first, second, third and fourth accelerometer equally spaced around the circumference of a circle, with their sensitive axes tangential to the circle, and arranged in opposing pairs with the first accelerometer opposite the second, and the third accelerometer opposite the fourth. In use the accelerometers are spun around an axis normal to the circle which passes through its center. A summing amplifier receives the outputs of the accelerometers and combines them in a manner to cancel the common mode output signals and so produces all instrument output. One or more feedback loops extend from the instrument output to one or more of the accelerometers to compensate for errors.

Abstract: Catalysts containing a carbonate or carbonates, particularly Group IA and IIA carbonates, may be hardened sufficiently to be useable in fluidized bed reactors. The catalysts are heated to at least 700.degree. C. in an atmosphere containing carbon dioxide under a partial pressure above the dissociation pressure of the carbonate form of the catalyst.

Abstract: A liquor of the Bayer process, as defined, is contacted with manganese dioxide to oxidize organic material in the liquor. When the liquor is the seed wash liquor, oxalates in particular are oxidized.

Abstract: Deashing of coal is achieved by oil agglomeration and subsequent separation of a carbon oil phase. The oil is removed by steam stripping after the coal oil agglomerates have been disintegrated. The fine coal product can be used in steam generating plants such as power stations.

Abstract: This specification discloses an easy-opening closure for a can end which comprises an opening formed by partially severing a portion from the can end to leave the portion attached thereto by an integral neck, and a closure member formed from said severed portion and which is larger than said opening. The sheet metal adjacent the free edge of the opening is downwardly turned while the sheet metal adjacent the free edge of the closure member is upwardly turned, said free edges being in contact with or in close proximity to each other. A sealant is applied at least in the region of the free edges if required by the purpose for which the can end is to be used.