Abstract: A spectrophotometer system includes an optics block housing an excitation lamp and a cell for receiving a gas to be detected. The excitation lamp excites atoms of the gas to be detected to produce photons. The spectrophotometer system also includes a photo-multiplier tube assembly and an analog-to-digital converter. The photo-multiplier tube assembly detects the photons, and produces an analog output accordingly. The analog-to-digital converter converts this analog output to a digital output. The photo-multiplier tube assembly and the analog-to-digital converter of a spectrophotometer system are calibrated together so that a zero input to the analog-to-digital converter may be defined as an absence of photons. The optics block is configured to minimize scattering of light, without a lens, so that the output of the spectrophotometer system is a function of the number of atoms of the gas to be detected and not of scattered light.

Abstract: in a hot combustion gas stream are removed therefrom by oxidizing the elemental mercury, to form a mercury compound, and adsorbing the mercury compounds on adsorbent particles such as activated alumina. Oxidation is catalytically promoted. After adsorbing a substantial quantity of mercury compounds, the spent adsorbent particles can be regenerated and re-used by heating the particles to decompose and drive off the mercury compounds. In another embodiment, oxidation of the elemental mercury is catalytically promoted at a catalyzing station, and the mercury compounds are removed from the gas stream by scrubbing.

Abstract: An oxidation resistant, non-consumable anode, for use in the electrolytic reduction of alumina to aluminum, has a composition comprising copper, nickel and iron. The anode is part of an electrolytic reduction cell comprising a vessel having an interior lined with metal which has the same composition as the anode. The electrolyte is preferably composed of a eutectic of AlF.sub.3 and either (a) NaF or (b) primarily NaF with some of the NaF replaced by an equivalent molar amount of KF or KF and LiF.

Abstract: Finely divided particles of alumina are electrolytically reduced to aluminum in an electrolytic reduction vessel having a plurality of vertically disposed, non-consumable anodes and a plurality of vertically disposed, dimensionally stable cathodes in closely spaced, alternating arrangement with the anodes. A horizontally disposed, gas bubble generator is located at the vessel bottom, underlying the cathodes and the spaces between each pair of adjacent electrodes. The vessel contains a molten electrolyte bath composed of (1) NaF+Alf.sub.3 eutectic, (2) KF+AlF.sub.3 eutectic and (3) LiF. The alumina particles are maintained in suspension in the molten electrolyte bath by rising gas bubbles generated at the anodes and at the gas bubble generator during the reduction process.

Abstract: The tearing strength of paper is improved by providing a furnish in which the fiber content is predominantly refined fiber with a minor amount, preferably 2 to 10 wt. %, of added unrefined fiber having incorporated therein a heat activatable bonding agent, particularly starch. The bonding agent adheres to and coats the added fiber without chemically reacting with the fiber. A cationic material, particularly polyethyleneimine, is premixed with the raw starch to cause it to adhere to the added fiber. During heat drying of the formed paper the starch is gelatinized to effect enhanced bonding of the added fiber.

Abstract: A cell for the electrolytic reduction of alumina to aluminum comprises an electrolyte bath composed of halide salts having a density greater than aluminum but less than alumina. A non-consumable anode is located at the bottom of the bath, and a dimensionally stable cathode coated with titanium diboride is spaced above the anode and totally immersed in the bath. Particles of alumina are introduced into the bath where the alumina dissolves and forms ions of aluminum and oxygen. The oxygen ions are converted at the anode to gaseous oxygen which bubbles upwardly through the bath, agitating the bath. As a result, the bath is substantially saturated with dissolved alumina in the region of the anode, and the build-up of a layer of undissolved alumina on the anode is prevented. The aluminum ions are converted to metallic aluminum at the cathodes, and molten aluminum accumulates as a pool atop the bath above the cathodes.