Abstract: The present invention relates to a method for the production of refractory oxide powders by pyrolyzing with laser energy a metal- and oxygen-containing organic chemical species characterized by the following properties: (a) some or all of the organic fragments (ligands) are bound to the metal by one or more metal-oxygen bonds, (b) the chemical species is able to absorb laser energy, preferably from a CO.sub.2 laser, in a vibrational mode, (c) the chemical species can be obtained in a gas state, at a temperature below the decomposition temperature.

Abstract: An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings comprising an electrolyte containing trivalent chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising an ion selected from the group consisting of scandium, yttrium, lanthanum, titanium, zirconium, hafnium, molybdenum, arsenic, selenium, tellurium, cerium, uranium, and tin present in an amount effective to maintain the concentration of hexavalent chromium ions formed in the bath at a level at which satisfactory chromium electrodeposits are obtained.

Abstract: An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings comprising an electrolyte containing trivalent chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising a metal ion selected from the group consisting of Gold, Silver, Platinum, Palladium, Rhodium, Iridium, Osmium, Ruthenium, Rhenium, Gallium, Germanium, Indium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, and Praseodymium present in an amount effective to maintain the concentration of hexavalent chromium ions formed in the bath at a level at which satisfactory chromium electrodeposits are obtained.

Abstract: An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings comprising an electrolyte containing trivalent chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising neodymium ions present in an amount effective to maintain the concentration of hexavalent chromium ions formed in the bath at a level at which satisfactory chromium electrodeposits are obtained.

Abstract: Chromium trioxide is made by reacting sodium dichromate with sulphuric acid in an aqueous reaction mixture, evaporating the resultant liquor to cause crystallization of most of the chromium trioxide and to cause the concentration of sodium sulphates to be close to but below that at which sulphate crystals start to form, and separating the chromium trioxide crystals from the evaporated liquor. The liquor may then be cooled so as to cause crystallization of sodium sulphates, generally as sodium bisulphate, and the resultant liquor, after separation of the crystals, may be recycled to the reaction mixture containing dichromate and sulphuric acid.

Abstract: Ferromagnetic chromium dioxide is produced in a continuous operation by feeding a preheated paste of hydrated chromium oxides and additives into a twin screw reactor, reacting at elevated temperature and pressure for a short time while venting oxygen and steam, injecting water near the end of the reaction zone to form a viscous chromium dioxide-water mixture, and cooling while passing through a pressure letdown extruder.

Abstract: This invention relates to a process for stabilizing ferromagnetic chromium dioxide in respect of water and oxidizable organic compounds which it may contact in magnetic tapes. The process is applicable to a starting CrO.sub.2 having good magnetic properties, i.e. a coercive force not lower than about 400 Oersted, a maximum magnetic induction B.sub.m not lower than about 2500 gauss, and a magnetic induction B.sub.r not lower than about 1600 gauss. The CrO.sub.2 is subjected to a heat treatment at a temperature ranging from 300.degree. to 390.degree. C. in the presence of a gas stream not exerting any oxidizing or reducing action on the compounds of trivalent, tetravalent and hexavalent chromium. Suitable gases are, for example, nitrogen, helium and argon.

Abstract: Disclosed is a process for reducing hexavalent chromium [Cr(VI)] in aqueous solutions to trivalent chromium [Cr(III)] by reacting a catalyzed hydrazine composition with the hexavalent chromium at a pH in the range from about 6.0 to about 8.0 to form an aqueous slurry of trivalent chromium compound, said catalyzed hydrazine composition comprising(a) a hydrazine compound,(b) at least 0.0005 parts by weight of a quinone compound per one part of hydrazine compound; and, preferably;(c) at least about 0.0005 parts by weight of an organometallic complex per part of hydrazine compound, said organometallic complex being the reaction product of:(i) a hydroxide selected from the group consisting of cobaltous hydroxide and manganous hydroxide; and(ii) at least one organic ligand selected from the group consisting of unsubstituted and substituted amino derivatives of carboxylic acids and salts thereof.The solid particles of trivalent chromium may then be separated from the aqueous solution by conventional means (e.g.

Abstract: A process for the manufacture of ferromagnetic chromium dioxide modified with foreign elements, by reacting oxides of trivalent and hexavalent chromium under superatmospheric pressure at an elevated temperature in the presence of water and of antimony(III) oxide as modifier, with or without other modifiers in an amount not exceeding 15% by weight, wherein the antimony(III) oxide employed as modifier is, to the extent of more than one-third, present as the senarmontite cubic modification, has a specific surface area, measured by the BET method, of from 1.5 to 15 m.sup.2 /g, and is added in a total amount of up to 0.5% by weight, based on the resulting chromium dioxide.

Abstract: A method of recovering chromium values and potential energy from liquid and solid leather tannery wastes comprising pyrolyzing the tannery wastes to produce a burnable fuel product comprising gases and liquids and a substantially solid chromium-containing residue, recovering chromium compounds from the solid residue and using the fuel to supply energy for the system.

Abstract: Chromic oxide of very low (below 40 ppm) insoluble sulphur content is obtained by calcination of a less pure product at a temperature above 1100.degree. C. for at least 10 minutes.

Abstract: Chromium trioxide contaminated with sulphate is purified by washing with an aqueous purifying wash liquor, generally water or aqueous chromic acid, while at a temperature above 50.degree. C. and centrifuging the washed product. Washing is generally conducted on the centrifuge. The chromium trioxide is preferably made by reacting sodium dichromate with from 2.4 to 2.8 mols sulphuric acid. The process can be operated to produce a novel product consisting of crystalline, non-fused, chromium trioxide that is substantially pure. The novel product can be in the form of pellets.

Abstract: A process and apparatus for the manufacture of ceramic oxide fibers from solvent solution. The process comprises spinning a solution of a ceramic oxide precursor through openings having a diameter of from about 0.3 to about 1.5 millimeters, attenuating the resulting fibers with a stream of air to a diameter of less than 10 microns and heating the fibers in an oxygen atmosphere to form ceramic oxide fibers having a diameter of less than 5 microns. The apparatus comprises a hollow rotatable disc having about 0.3 to about 1.5 millimeter holes in its circumferential edge; means for rotatably mounting the disc; means for introducing a solution of a ceramic oxide precursor into the disc; means for rotating the disc to force solution through the openings in fiber form; means for attenuating the fibers with a stream of air; and means for calcining the fibers.

Abstract: A method has been devised for removing hexavalent chromium from concentrated aqueous alkali metal chlorate solution by reacting the solution with an inorganic sulfur containing compound and separating divalent and trivalent chromium compounds from the solution. Alkali metal hypohalites may be simultaneously removed from the chlorate solution by reaction with excess inorganic sulfur containing compound.

Abstract: A sintered, polycrystalline and fully dense chromium oxide body is prepared by heating a Cr.sub.2 O.sub.3 powder compact at relatively low temperature on condition that a liquid of low-melting chromium oxide compound is formed partially in the compact during heating. In practice the compact buried in carbon powder is heated above 1350.degree. C. The porosity of the sintered body is controlled by changing the proportion of the amount of coarse particles and fine particles in the starting Cr.sub.2 O.sub.3 powder. A sintered and crack-free body with uniform microstructure and without abnormal grain growth of Cr.sub.2 O.sub.3 is obtained by the sintering of Cr.sub.2 O.sub.3 powder compact with Cr metal powder.

Abstract: Transition metal hydroxides of the first transitional series are prepared by reacting a transition metal with water, a nitrogen-containing compound, one or more aliphatic or alicyclic monocarboxylic acids containing at least eight carbon atoms and a diluent in the presence of oxygen. Only small amounts of the acid and nitrogen-containing compound are required. The reaction mixture also can contain dispersants. The method of the invention avoids the corrosion and pollution problems which are present in some prior art processes. The transition metal hydroxides prepared in accordance with the invention are free of salt contamination.

Abstract: A ferromagnetic chromium dioxide stabilized by coating the particles thereof with a stabilizing substance is disclosed, wherein the stabilizing substance consists essentially of an equimolecular mixture of Fe.sub.2 O.sub.3 and MnO or of a mixture of ferrite MeFe.sub.2 O.sub.4 with oxides Fe.sub.2 O.sub.3 and MeO, wherein Me represents Cu, Co, Zn or Mg and wherein the molar ratio Fe.sub.2 O.sub.3 /MeO is equal to 1, the quantity of the ferrite in the mixture being such as results from calcining, at temperature between 250.degree. and 350.degree. C., equimolecular quantities of Fe.sub.2 O.sub.3 and MeO. A process for obtaining the stabilized CrO.sub.2 is also disclosed wherein the CrO.sub.2 is dispersed in water and on it are co-precipitated Fe(OH).sub.3 and Mn(OH).sub.2 or Me(OH).sub.2 in stoichiometric quantities with respect to each other; after which the CrO.sub.2, in admixture with the hydroxides, is separated from the water, dried at a temperature not exceeding 100.degree. C.

Abstract: A process for the production of low sulphur chromium(III) oxide comprising annealing at a calcining temperature from about 800.degree. C. to 1100.degree. C. a mixture of alkali metal chromate and about 0.7 to 0.96 times its molar amount of ammonium sulfate, and separating the chromium(III) oxide formed from the alkali metal salt. Advantageously the ammonium sulfate in the form of a concentrated solution is mixed with solid alkali metal dichromate and the mixture thereafter is adjusted prior to calcination to a water concentration of less than about 15% by weight of water.

Abstract: A process and apparatus for obtaining a more concentrated solution of components such as chromium containing anions by the use of ion exchange beds. A solution containing the component to be concentrated is passed through a first bed in which the component is taken up. A second solution containing a component of opposite charge from the first component is passed through the first bed to take up the component from the first bed and then through a second bed capable of taking up the second component from the solution. The second solution is passed from the first bed directly to and through the second bed, and both beds are rinsed following passage of the second solution therethrough by passing a rinse solution through the second bed and then directly to and through the first bed in a direction opposite to the direction in which said second solution passed through the beds.

Abstract: The present invention concerns a stabilized ferromagnetic chromium dioxide and a process for obtaining the same. More particularly, the present invention relates to ferromagnetic chromium dioxide stabilized by means of the coating of its particles with a stabilizing substance, characterized in that the stabilizing substance is selected from the group consisting of a zinc, aluminum or chromium (III) polyphosphates having a high molar ratio phosphorus/metal and having, depending on the metal, the following formula: P.sub.2 O.sub.5.nZnO.mH.sub.2 O wherein "n" in general is comprised between 0.286 and 0.667 while "m" is generally comprised between 0 and 2.570;P.sub.2 o.sub.5.nAl.sub.2 O.sub.3.mH.sub.2 O wherein "n" is in general comprised between 0.225 and 0.500, while "m" is generally comprised between 0 and 2.68;P.sub.2 o.sub.5.nCr.sub.2 O.sub.3.mH.sub.2 O wherein "n" is in general comprised between 0.143 and 0.333, while "m" is generally comprised between 0.002 and 2.46.

Abstract: A process for the preparation of a chrome-tanning agent and Glauber's salt from sodium bisulphate contaminated with chromium compounds obtained as by-product from the manufacture of chromic acid from solid sodium dichromate and sulphuric acid, comprising(a) treating an about 20 to 70% aqueous sodium bisulphate solution which contains chromium compounds and is acid with sulphuric acid with sulphur dioxide until all the chromium is present in the form of chromium (III);(b) adding sodium hydroxide to the reduced solution until it has a pH of between about 4 and 5;(c) adding sodium carbonate to the solution to a pH of between approximately 8 and 8.5, thereby precipitating chromium (III) hydroxide;(d) separating off the precipitated chromium (III) hydroxide; and(e) evaporating the filtrate left after removal of the chromium (III) hydroxide to yield solid sodium sulphate.

Abstract: A chromium chromate complex, obtained by partial reduction of chromic acid in aqueous media with an organic reducing agent, is converted to pigment form by evaporating the resulting aqueous composition to dryness and sub-dividing the obtained solid mass to suitable size. The obtained pigment, with or without intimately associated extenders, incorporated in a conventional vehicle, serves as a corrosion inhibitor in metal coating compositions.

Abstract: An arc heater method and system for producing a high energy source characterized by a housing forming a mixing compartment, a plurality of arc heaters radially mounted on the housing and communicating with the mixing compartment, a reactor communicating with the downstream end of the mixing compartment with a reduced opening therebetween, inlet means at the downstream end of the compartment for introducing an oxidizable metal compound into the reactor, and means within the mixing compartment for flowing superheated gases from the arc heaters at the upstream end of the compartment and into the reactor.

Abstract: Process for the removal of chromium and zinc corrosion inhibitor compounds from cooling tower blowdown streams, comprising contacting the water of said streams first with a weakly basic anion exchange resin and then with a weakly acidic cation exchange resin.

Abstract: A method for decontaminating waste materials, wherein the residue of water leaching of the roasted chromium mineral containing water soluble hexavalent chromium compounds is wet ground and classified until obtaining such a granulometrical distribution that not more than 5-10% of the particles have an average size larger than 0.4 mm, and 40-60% of the particles have an average size less than 0.8 mm, and is then subjected to wet treatment under vigorous stirring at about 100.degree. C. with sulphur, in an aqueous emulsion of akaline or alkaline-earth sulphide for 1-4 hours, the percentage of solids in the reactor being in the range of 1-60%, preferably 30-35% by weight; and wherein the reacted slurry is thickened and filtered to provide the restored or decontaminated earth and an effluent, which is partly recycled to grinding or to reaction.

Abstract: Disclosed is a method of preparing a crystalline pigmentary chromic: oxide, Cr.sub.2 O.sub.3, having a mass average particle size less than about 1 micron. According to the disclosed method, a substantially dry solid composition of an alkali metal chromate and carbon is heated in an inert atmosphere to a temperature of above about 500.degree. Centigrade and maintained thereat until substantially all of the alkali metal chromate is decomposed. Thereafter, the solid composition is cooled while still in an inert atmosphere and thereafter pigmentary Cr.sub.2 O.sub.3 is recovered therefrom.

Abstract: Chromium dioxide CrO.sub.2 is prepared by oxidizing hydrated trivalent chromium oxide Cr.sub.2 O.sub.3, xH.sub.2 O, where x is at least 1, at a temperature of at least 350.degree. C and under pressures of at least 2 kilobars. The reaction is carried out in an oxidizing medium, which is a solid or an aqueous liquid solution, essentially constituted by a compound of the formula HXOy, zH.sub.2 O, wherein X represents an atom of chlorine or iodine, y is a positive integer less than or equal to 4, and z is a number which is a function of the dilution of said compound in the solution or a function of the crystallization water in the case of a solid oxidizing agent.The product is useful in any device requiring a compound which is ferromagnetic at a temperature less than 116.degree. C and notably in magnetic tapes.

Abstract: A process is disclosed for incinerating tannery waste solids containing organic material and chromium which comprises burning at least one ton per day of said waste in the combustion zone of an industrial furnace at a low temperature, preferably between about 800.degree. F. and 1200.degree. F., to convert at least a portion of the organic material to gases and the chromium to ash, removing the gases from the combustion zone and subjecting them to further oxidation, and removing the ash from the furnace. The waste solids include sludge separated from liquid waste, leather scrap, or preferably both. By controlling temperature, waste composition, or both, the chromium in the ash can be obtained in either trivalent or hexavalent form. The hexavalent chromium can be extracted with solvent for reuse in the tanning process. Trivalent chromium, with or without carbon, can be recovered as chromic oxide in an improved stable form for landfill, storage or shipment to a reprocessing center.

Abstract: Chromates are removed from aqueous alkali metal chlorate solutions by either of two processes. In the first process, a water-soluble sulfide is added to react with the chromate, and then a ferrous salt is added. The soluble sulfate is converted to elemental sulfur and the chromate is converted to an insoluble trivalent Cr-containing material which is removed from solution. In the second process an "iron mud" is prepared by reacting a ferrous salt with sodium hydroxide and added so as to precipitate insoluble trivalent chromium-containing material.

Abstract: Composition comprising a highly ferromagnetic CrO.sub.2 having deposited on the surface thereof an insoluble or sparingly soluble compound, thereby rendering the composition essentially non-reactive to water or oxidizable organic substances. Compound comprises either an oxide or hydroxide of Si and/or Ti.

Abstract: Disclosed are storable solid propellant compositions based on complex metal oron compounds of the general formula M(BH.sub.4).sub.x or M(BD.sub.4).sub.x, (where M equals a metal and x equals the valence of the metal M; M is an alkali metal or an alkaline earth metal; H is hydrogen, and D is deuterium) and ammonium salts of the general formula (NH.sub.4).sub.n Y or deuteroammonium salts of the general formula (ND.sub.4).sub.n Y (where Y represents an anion with a total charge of n; N is nitrogen, H is hydrogen, and D is deuterium) combined stoichiometrically or in varying molar ratios. The stoichiometric blend is employed in a method for producing hydrogen or deuterium that contains nitrogen as an inert diluent and is acceptable for use in HF/DF chemical lasers, the gas dynamic laser (GDL), or as a source to generate hydrogen containing an inert diluent.

Abstract: A sintered, fine grained, polycrystalline, essentially fully dense, essentially single phase Cr.sub.2 O.sub.3 body is prepared by sintering Chromium Sesquioxide (Cr.sub.2 O.sub.3) at essentially the equilibrium oxygen partial pressure (P.sub.O.sbsb.2) for the formation of Cr.sub.2 O.sub.3 from its elements at the sintering temperature. To achieve optimum theoretical density a second metal oxide dopant such as MgO, capable of controlling the grain size, is added.In addition, Cr.sub.2 O.sub.3 bodies are rendered more stable, and thus have a longer life, by maintaining over the body an atmosphere which is essentially equilibrium P.sub.O.sbsb.2 for the formation of Cr.sub.2 O.sub.3 from its elements at that temperature.

Abstract: A process for producing nickel oxide and other products in which percentages of metal powder, particularly nickel powder, and water are blended, the blend being subjected to a heat treatment to form the desired product. In the case of nickel oxide, the blend is exposed to air and temperature sufficient to form an oxide shell substantially about the powder particles, this treatment being followed by a final firing heat treatment.

Abstract: In the continuous production of low-sulfur chromium(III)oxide pigment comprising the steps of reducing a finely divided alkali metal chromate in a heated hydrogen-containing reaction zone at a temperature of about 900.degree. to 1600.degree. C, and precipitating the resulting chromium(III)oxide in the form of an aqueous dispersion, the improvement which comprises passing the reduction products from the reaction zone to a dwell zone and generating heat within said dwell zone to maintain the temperature therein in the range of about 900.degree. to 1600.degree. C. Preferably the dwell zone temperature is within 200.degree. C of that in the reaction zone and is maintained by introducing excess hydrogen into the reaction zone and consuming it in the dwell zone by introduction of oxygen. The resulting pigments exhibit a fuller green color.

Abstract: Aqueous process streams or waste waters destined for merging with public waters sometimes contain deleterious amounts of heavy metals, e.g., lead (Pb) compounds. The heavy metal compounds may be substantially removed or reduced to harmless levels by treating the acidic aqueous streams with chromate or dichromate ions, then heating the solution to oxidize organics and/or heavy metal-organics, then raising the pH to an alkaline pH to precipitate the heavy metal chromate, and separating the heavy metal chromate from the aqueous stream.

Abstract: CrO.sub.2 synthesized by the known hydrothermal reaction of CrO.sub.3 /Cr.sub.2 O.sub.3 /H.sub.2 O mixtures (including minor dopants) by the use of a reaction vessel having a hollow longitudinal core open at both ends. The core may have a cross section of convenient size and shape. This process results in shortened heating and cool/vent/dry cycles resulting in increased overall productivity despite the apparent reduced volume of the reaction vessel.

Abstract: A process of recovering and exploiting wastes from chromic anhydride production, wherein the slurry comprising a water suspension of solid waste residue from chromic anhydride processing is subjected to a first reaction stage with sodium chromate solution at a constant flow rate and such a density as to avoid precipitation of sodium sulfate, setting pH to 2-8 by adjusting the slurry flow rate, and finally separating by filtering insoluble chromium chromate formed from the sodium bichromate and sodium sulfate solution.

Abstract: In the production of chromium oxide green pigment by heating a substantially stoichiometrically equivalent mixture of sodium dichromate dihydrate and an ammonium salt selected from the group consisting of the sulfate and chloride, the improvement which comprises dry mixing sodium dichromate dihydrate having a particle size less than 2 mm with the ammonium salt having a particle size less than about 0.5 mm, heating the resulting mixture over a period of about 15 minutes to a pigment-forming temperature of about 800.degree. to 1100.degree. C, calcining the mixture at a temperature in that range, and separating the formed pigment from the salts. To the mixture prior to heating there may be added sodium hydroxide solution, boron compounds such as borax and/or organic modifiers such as sawdust which improve the color and tinting strength of the resulting pigment. The pigments are brighter, and of higher tinting strength than heretofore produced.

Abstract: A method for reducing the residual chromate level in effluent waters comprising catalytic reduction of the chromate ion by hydrogen to the trivalent chromium state and removal of the chromium by passage through a cation exchange resin column or by base precipitation in a settling pond.

Abstract: Modified ferromagnetic chromium oxide having an intrinsic coercive force above 150 Oersteds, a Curie temperature lower than that of unmodified chromium dioxide, and a specific magnetization in the range of 50-110 emu/gm., is prepared by heating material containing chromium (III) and sulfur in a form to yield upon oxidation a ferromagnetic chromium oxide with substitutional sulfur enhancing its magnetic properties.

Abstract: Hydrogen is produced by the reaction of water with chromium sesquioxide and strontium oxide. The hydrogen producing reaction is combined with other reactions to produce a closed chemical cycle for the thermal decomposition of water.

Abstract: A method of treating solid waste material containing minor amounts of water soluble chromium compounds with a reductant, particularly sulfide ions, to convert the soluble chromium to an insoluble state, and produce a solid waste from which substantially no chromium can be leached by water, as by exposure to rain.

Abstract: Ferromagnetic chromium dioxide is prepared by thermally decomposing, at a temperature of 250.degree.-500.degree.C, and a pressure of at least 80 atmospheres, a mixture of hydrated trivalent chromium chromate of the formula Cr.sub.2 (CrO.sub.4).sub.3.nH.sub.2 O, wherein n is 7-12, and antimony or a compound thereof, the amount of antimony in the mixture being between 0.2 and 1.8% by weight based on the weight of anhydrous Cr.sub.2 (CrO.sub.4).sub.3. In another embodiment, other known modifiers for chromium dioxide, such as lanthanum, lithium, strontium, iron or lead, or a compound thereof may be added to the mixture of chromium chromate and antimony. The amount of said other modifiers is between 0.1 and 2% by weight of the element, based on the weight of anhydrous Cr.sub. 2 (CrO.sub.4).sub.3.

Abstract: A method for producing, under a low pressure such as an ambient atmospheric pressure, a ferromagnetic chromium oxide having a sufficiently high saturation magnetization and, if necessary, sufficiently high coercive force as well. The main feature of this method is to use H.sub.2 O.sub.2 in conjunction with CrO.sub.3 and, if necessary, Te, Sb or an alkali element as well and to heat them.

Abstract: Olated chromium (III) nitrate is obtained by dissolving hexaaquochromium (III) nitrate in a C.sub.1 -C.sub.4 alcohol or in tetrahydrofuran, any of them containing less than about 10% of water. The preferred alcohol is isopropyl alcohol. The preparation can also start with chromium trioxide, which is reduced to chromium (III) nitrate by a reducing alcohol, such as isopropyl alcohol, in the presence of nitric acid. Alternatively, the reduction can be accomplished in a nonreducing organic solvent, such as tetrahydrofuran, by hydrogen peroxide in the presence of nitric acid. Highly olated chromium nitrate is an excellent coupling agent for reinforced thermoplastic composites. Olation in the presence of a carboxylic acid or addition of a carboxylic acid to the olated chromium (III) nitrate gives carboxylic acid-olated chromium (III) nitrate complexes, which are useful as coupling agents or as mold release agents.

Abstract: A continuous method is provided for reclaiming chromium compounds which heretofore were discharged as industrial waste from chrome liquor tanneries. The method includes continuous agitation of chrome sludge along with continuous filtration and movement through successive filtering zones. This method is both economically attractive and vital from an ecological standpoint. The reclaimed chromium values are in condition for reconstitution into fresh chrome-tanning liquors.