baber/WOPTO huggingface dataset:
Patent CH-595930-A5 (CH)
Title: Heated wick for melting and removing solder from joints
Inventor: FISCHER ERICH
IPC: B23K3/08
Filed: 1975-07-29
Abstract: Metal wick is made of several elements and used for sucking up molten solder.  At least the outer surface of the wick has a continuous coating of a lacquer, providing protection against corrosion of the clean metal under the lacquer.  The surface of the metal elements is pref. cleaned, and at least the outside of the wick lacquered.Each metal element (e.g. narrow metal tape) is pref. cleaned and lacquered; and the wick may also be coated with strips or spots of flux; a non-metallic thread coated or impregnated with flux may be used between the wick elements.  The wick elements pref. consist of tape, which is cleaned and/or pickled, then formed into braid.Used for rapid unsoldering of joints, e.g. soft-soldered joints in electronic circuits.  The wick is heated to above the m.pt. of the solder and then placed on the soldered joint to melt the solder and suck it up the wick.
Patent CH-592226-A5 (CH)
Title: Swimming pool covering roller shutter - has hollow profile and transparent and heat absorbing walls for warming water by sunlight
IPC: E04H4/08
Filed: 1975-09-11
Abstract: The cover for a swimming pool consists of several interconnected flat profiles. The latter are a hollow and able to float. This cover in the form of horizontal roller shutter protects swimming pool against dirt and fallen leaves. The cover also prevents excessive cooling of the pool water overnight. The water is warmed through this cover when sunlight impinges on cover. The air side wall (0) of a flat profile is made from material transparent to sunshine. The water side wall (10) absorbs the incident sunlight. The air side wall can be made from glass or transparent plastics whose outside face is covered with sunlight absorbing layer. The water side wall is made from a metal whose inner face is blackened.
Patent CH-621041-A5 (CH)
Title: Rodenticidal composition.
Inventor: DREIKORN BARRY ALLEN
IPC: A01N33/18
Filed: 1976-09-24
Abstract: The rodenticidal composition is an edible composition and contains a diphenylamine as active component. The diphenyl is selected from the following group consisting of:     2,4,6-tribromo-2',4',6'-trinitrodiphenylamine,   2,4-dichloro-2',4',6,6'-tetranitrodiphenylamine,   2,3,4,5,6-pentachloro-2',4',6'-trinitrodiphenylamine,   2,3,4,5,6-pentafluoro-2',4',6'-trinitrodiphenylamine,   2,4,6-trichloro-2',4',6'-trinitrodiphenylamine, 3,5-bis(trifluoromethyl)-2',4',6'-trinitrodiphenylamine, 2,4-dinitro-3',5',6-tris(trifluoromethyl)diphenyamine,   2,4-dinitro-4',6-bis(trifluoromethyl)diphenylamine, 2,3,4,5,6-pentachloro-2',4'-dinitro-6'-trifluoromethyldiphenyl-ami ne,   2,4-dinitro-2',4',6'-trichloro-6-trifluoromethyldiphenylamine,   2,4,6-tribromo-2',4'-dinitro-6'-trifluoromethyldiphenylamine 2,4-dibromo-6-chloro-2',4'-dinitro-6'-trifluoromethyldiphenyl-amin e, 4-bromo-2,6-dichloro-2',4'-dinitro-6'-trifluoromethyldiphenyl-amin e and 2,4-dibromo-2',4'-dinitro-6'-trifluoromethyldiphenylamine. l-
Patent CH-604471-A5 (CH)
Title: Open-mesh woven fabric ground-covering
Inventor: SEITH ROBERT T
IPC: A01G25/00
Filed: 1974-09-24
Abstract: Open-mesh woven fabric ground-covering consists of large number of sections joined together, and paper, metal, plastics or other insertion-strips
Patent CH-601930-A5 (CH)
Title: Hollow profile shelf rail
Inventor: SCHIFF HEINZ
IPC: H01R25/16
Filed: 1975-10-08
Abstract: Hollow profile shelf rail has electrical conductor arrangement and bracket insertion recesses
Patent CH-574800-A5 (CH)
Title: Punching tool for making cotton wool pads - has cutting die and punch with sliding spring loaded conical nose
IPC: B26F1/14
Filed: 1974-12-16
Abstract: The punching tool is used for punching out of circular pads from fibrous material, especially from cotton wool by a punch and a die. The circular cotton wool pads are used for example for the application of powder on the skin or for removal of cosmetics. The cutter ensures that these round cotton wool pads do not fray and split at the edges. The die (2) with cutting edge (3) and the cone (7) of the punch meet for cutting a pad. The punch (1) is made in a number of sections and the conical part (4) can slide on the guiding punch part (8) in the punch travelling direction. Between the conical section (4) and the conical section guide is arranged a spring (6) in the form of a rubber ring and an ejector (11) is fitted into the punch nose.
Patent CH-559330-A5 (CH)
Title: Turbine feed valve - operates in non flowing conditions on supply pipe
IPC: F16K5/14
Filed: 1972-12-08
Abstract: The valve body (1) houses a valve disc (2) mounted on a horizontal pivot (4) operated by a hydraulic jack linked to a lever attached to the valve disc. Under non flowing conditions i.e. when the water supply to the turbines has been cut off, there is no pressure difference across the valve so it can easily be closed by admitting high pressure water to the jack. A supply valve (11) is closed and another (14) opened, maintaining high pressure on the upstream side of the valve and releasing the pressure from the downstream side so creating a pressure difference across the valve which presses the disc (2) onto the seat (6).
Patent FR-2038592-A5 (FR)
Title: Tunnel kiln for the firing of refractory - ceramic products
IPC: F27B9/30
Filed: 1969-03-19
Granted: 1971-01-08
Abstract: Tunnel kiln is used for firing bricks and provides for the material to be piled onto carriages which are run through the kiln at a specific speed. Exhaust gases are moved through the kiln in the opposite direction to the path of travel of the material to be fired. At the hottest part of the cooling zone there is a tapping point connected with a recuperator for the exhaust gases, and this is associated with a ventilator which recirculates the exhaust gases. Exhaust-gas and hot-gas branch conduits are provided and the combustion zone is provided with connecting pieces for introducing secondary air.
Patent FR-2035391-A5 (FR)
Title: Prepn of storage stable solutions of amino- - plast impregnation resins
IPC: C08G12/34
Filed: 1970-02-13
Granted: 1970-12-18
Abstract: Preparation of storage stable solutions of aminoplast impregnation resins. Process comprises (1) condensing, in a zone of pH above 6, in the aqueous phase, at 75-100 degrees C melamin and up to 10 moles of urea (per mole melamine), 0.01-0.5 mole of an alkali salt of an amido sulphonic acid and formaldehyde in an amount of 0.2-0.8 mole per gram atom of hydrogen atoms attached to the nitrogen of the aminoplast generators and (2) interrupting the condensation just before the formation of condensation products insoluble in water. The solutions are used to prepare impregnated papers or supports, for improving wood, esp. to give hard plastic surfaces resistant to radiation, abrasion, water, flames.
Patent FR-2086935-A5 (FR)
Title: German silver contg manganese - which is cold workable
IPC: C22C9/04
Filed: 1970-04-14
Granted: 1971-12-31
Abstract: German silver type alloy contg. Mn comprises by wt. 8-18% Ni, 3-10% Mn, 0.5-2.5% Pb, 38.6-40.6 Zn, balance Cu, in which Zn % + Mn % (1.35-0.07 (Mn %) -0.3 Ni % . The alloy has a microstructure contg. 25.75% beta phase, balance alpha phase. The beta-phase improves hot working, while the addition of the manganese improves the cold working properties.
Patent FR-2088946-A5 (FR)
Title: Reduction process - for metal oxides
IPC: C01B31/30
Filed: 1970-04-30
Granted: 1972-01-07
Abstract: The oxide mixed with a suitable quantity of C is passed through a furnace traversed by a column of ionised gas at high temp. The metal oxide is thus reduced to the metal and the CO2 formed evacuated from the chamber the metal vapour is rapidly quenched by gas such as Ar or pref. by a spray of the same metal in a cooling tower. The liquid metal is collected at the bottom of the tower and may be tapped off at intervals. May be used for prep. of Al, Mg, Fe, Zr etc.
Patent FR-2093353-A5 (FR)
Title: In-service cleaning of cooling water systems
IPC: C02F5/08
Filed: 1970-06-11
Granted: 1972-01-28
Abstract: A cooling H2O system, having Fe2O3 and hardness deposited on the internal metal surfaces, is cleaned by a 2-stage method: an alkali metal or NH4 salt of an amino polycarboxylic acid is added to bring the pH to 7-12 and dissolve and complex the hardness deposits; after circulation, a mixture of the alkali metal or NH4 salt of an aminopolycarboxylic acid and an acidifying agent is added to dissolve and complex the Fe2O3 deposits and bring the pH to 3-6. After circulation, the cleaning soln. is displaced by make-up H2O. The process removes Fe2O3 and hardness from cooling H2O systems, such as an air-conditioning system.
Patent FR-2098935-A5 (FR)
Title: Labels or pictures - with decorations using support sheet coated with pressure sensitive adhesive eg polyolefin coated with poly
IPC: G09F3/02
Filed: 1970-07-31
Granted: 1972-03-10
Abstract: Labels, panels or pictures or similar faces with signs or decorations are produced by (a) forming a first sheet with a support coated on at least one side with a layer of a pressure sensitive adhesive, (b) forming a second transfer sheet with a support carrying a transferable skin, (c) combining the two sheets so that the adhesive layer and the transfer able skin are directed towards each other, (d) applying to the combination a predefined decoration under a definite pressure, (e) cutting a corresponding decoration in the transferable skin, (f) transferring the cut out decoration onto the adhesive layer so that it becomes bonded, and (g) separating the two original sheets from each other, and (h) opt. coating the sheet carrying the decoration with a protective skin. Pref. the adhesive is of polyurethane, silicone, cross linkable acrylic resin, polyvinyl ether, or a rubber.
Patent FR-2068919-A5 (FR)
Title: Removal of sulphur cpds from gases by oxidn with catalyst soln
IPC: B01D53/48
Filed: 1970-11-03
Granted: 1971-09-03
Abstract: Catalytic oxidation esp. of H2S, SO2, mercaptans, COS2, CS2 by contact with aq. solutions of organic oxidants e.g. bis-beta-hydroxyethyl sodium glycinate, diethylene-triaminopentacetic acid, beta-hydroxymethyl-iminodiacetic acid and complex forming metals from groups II, V, and VIII esp. Fe, Cu is used for purification of effluent gases, combustion gases etc. Oxygen (>0.30%) is added either to the purification column or separately. Sulphur is separated from the wash liquors by reduction to elemental S or organic sulphur/oxygen compounds. A wide range of compounds can be removed with one wash liquid in one operation, independent of pH of soln.
Patent FR-2078463-A5 (FR)
Title: Photographic etching exposure matrix prodn
IPC: G03F1/54
Filed: 1971-02-11
Granted: 1971-11-05
Abstract: Exposure-matrix for photographic etching is produced by placing a layer of lead sulphide on a glass plate, applying an etching matrix, and etching away the uncovered parts of the lead sulphide layer with chromic - sulphuric acid in several stages, the etched parts being treated with a complex forming compd. after each partial etching in order to remove the formed etching products after which etching is continued. Specif. the complex forming agent is disodium salt of EDTA, ammoniacal tartaric acid, and a neutral soln. of nitrilotriacetic acid or diethylenetriamine-pentaacetic acid.
Patent FR-2176391-A5 (FR)
Title: Carbographic articles - eg typewriter ribbons, having high mechanical resistance, contg a synthetic thermoplastic polymer
IPC: B41J31/04
Filed: 1973-03-12
Granted: 1973-10-26
Abstract: The support comprises two films of polymers selected from linear polyesters, polypropylene and polyamides, bonded together in the cold by means of an interposed non-rigid adhesive. Specif. the support is 20-45 mu thick and the layer of non-rigid adhesive is 1-5 mu thick. That side of the support to which will be applied the ink layer is provided with a layer of a polymer selected from polyvinylidene chloride, polyacrylates, polyamides and melamines, to improve adhesion, this layer also pref. contg. finely divided silica to render the surface rough and also to improve adhesion.
Patent FR-2224987-A5 (FR)
Title: Board game simulating car racing on a track - uses transparent plastic cards to define speed and line of movement of cars
IPC: A63F9/06
Filed: 1973-04-05
Granted: 1974-10-31
Abstract: A car racing track game, costing less than similar games using model cars with electric motors. A board has a closed circuit track printed on it. Cars are represented by windows in transparent plastic cards. Each player has a coloured pencil and uses his skill to negotiate bends and avoid collisions and skids, but still choosing the fastest course for his car, by marking through a chosen window in the card. A set of cards represents the ratios of a gear box and the player must always change gears to simulate conventional practice.
Patent FR-2230226-A5 (FR)
Title: I.C. engine with auxiliary air injection - has auxiliary injection passage in cylinder wall and controlled by piston
IPC: F02B33/26
Filed: 1973-05-16
Granted: 1974-12-13
Abstract: The internal combustion engine is a four stroke reciprocating piston type. There is an air inlet port to the crankcase which is uncovered when the cylinder is at top dead centre. The air trapped in the crankcase is then compressed as the piston descends. At bottom dead centre the exhaust ports from the crankcase are uncovered, allowing the compressed air to pass into the cylinder. The charge already drawn into the cylinder is now diluted to the correct mixture strength before being compressed for the power stroke. Combustion now takes place as in conventional engines, but on the exhaust stroke the additional charge of air from the crankcase proveds scavenger air. Variations provide for the additional air charge to be supplied through a supercharger and for the charge to be metered.
Patent FR-2250375-A5 (FR)
Title: Single screw compressor or motor - each pinion tooth is longer on the low pressure side
IPC: F01C3/02
Filed: 1973-10-31
Granted: 1975-05-30
Abstract: The multi-start thread screw rotor (1) with threads (2) is mounted on a shaft (3) and engages the teeth (6) of the pinion (4) mounted on the shaft (5). The pinion teeth (6) have the one flank (13) longer on the low pressure side than the other flank (14) so that the surface of the tip of the tooth is oblique to the radius. The worm teeth are of corresponding form to the pinion teeth. The effect of this shape of tooth is that the gas is compressed to a much smaller volume at the instant that the space between consecutive worm teeth communicates with the delivery port yet the time for the gas to flow through the port is not reduced.
Patent CH-694803-A5 (CH)
Title: Stacking table for paper sheet stack e.g. for copier or printer, has air jets with air regulating valves incorporated in table surface and connected to pressurized air supply
Inventor: KUNZMANN BERND
IPC: B65H3/48
Filed: 2000-10-09
Abstract: The stacking table (10) has air jets (18) incorporated in the table surface (14) connected to a pressurized air supply, for providing air at a pressure of 5 psi, each air jet having a control valve for regulating the delivered air stream.
Patent DD-153092-A5 (DD)
Title: Vorrichtung zum spritzen von radial endlosen laufgummiringen
Inventor: KREBS GERD
IPC: B29C45/02
Filed: 1980-09-11
Abstract: Waehrend das Ziel der Erfindung in einer Erhoehung der Produktivitaet der Gesamtanlage und in einer Senkung des Anlagenaufwandes zu sehen ist, besteht die Aufgabe darin, eine einfache, schnelle Fertigungsweise von qualitativ hochstehenden Fahrzeugguertelreifen unter Verringerung oder Einsparung der zwischen den einzelnen Arbeitsschritten zurueckzulegenden Transportwege zu ermoeglichen. Dieses wird im wesentlichen mit der Vorrichtung zum Spritzen von radial endlosen Laufgummiringen dadurch erreicht, dass der Kern als elastische,nahezu inkompressible und im Durchmesser veraenderbare Guertelwickelscheibe ausgelegt ist. Diese wird durch einen metallischen, ringfoermigen Koerper als Unterbau gestuetzt und bei der die mit den Form-Schalen verbindbare oder fest verbundene Einspritzvorrichtung in bezug auf die Guertelwickelscheibe verschiebbar ist.
Patent DD-156911-A5 (DD)
Title: Verfahren zur herstellung von 7-oxo-1-azabicyclo(3,2,0)hept-2-ene-2-carbonsaeure-derivaten
Inventor: HIRACKA TETSUO
IPC: C07F9/568
Filed: 1981-03-03
Abstract: Die Erfindung betrifft ein Verfahren zur Herstellung von 7-Oxo-1-azabicyclo (3,2,O)hept-2-en-2- carbonsaeure- Derivaten mit starker antibakterieller Wirkung fuer die Anwendung als Arzneimittel. Ziel der Erfindung ist die Bereitstellung neuer stabiler antibakteriell wirksamer Verbindungen. Erfindungsgemaess werden Verbindungen der allgemeinen Formel (I) hergestellt, worin beispielsweise bedeuten: R hoch 1 Wasserstoff oder eine gegebenenfalls substituierte Alkylgruppe; X eine Oxygruppe, Thiogruppe, Sulfinylgruppe u.a.; A eine bi- oder trivalente gesaetigte aliphatische Kohlenwasserstoffgruppe; p 1 oder 2; R hoch 2 eine Azido-, Nitro- oder Cyanogruppe u.a.; m und n gleich oder verschieden, 0 oder 1.
Patent DD-203315-A5 (DD)
Title: Verfahren zur spaltung von polyalkylenglykol
Inventor: BARTLEY WILLIAM J
IPC: C07C27/04
Filed: 1982-09-30
Abstract: Die Erfindung betrifft ein Verfahren zur Spaltung eines Polyalkylenglykols, welches mindestens eine Ethergruppe enthaelt, beispielsweise Diethylenglykol. Ziel der Erfindung ist die Bereitstellung eines verbesserten Verfahrens zur Herstellung von Monoethylenglykol, mit dem hohe Ausbeuten erzielt werden koennen. Erfindungsgemaesz erfolgt die Spaltung an einer kovalenten Kohlenstoff-zu-Sauerstoff-Bindung durch Erhitzen des Polyalkylenglykols mit molekularem Wasserstoff in Anwesenheit eines Hydrierungskatalysators, z.B. Kupferchromit, zur Herstellung sowohl eines Monoethylenglykols als auch von Ethanol.
Patent DD-216479-A5 (DD)
Title: Brennstoffbriketts
Inventor: SCHAEFER GEORG H
IPC: C10L5/10
Filed: 1984-04-19
Abstract: Die Erfindung betrifft ein Verfahren zur Herstellung von Brennstoffbriketts. Ziel der Erfindung ist die Bereitstellung eines verbesserten Verfahrens, das Brennstoffbriketts mit guenstigen mechanischen Eigenschaften und einem vorteilhaften Brennverhalten liefert, deren Verbrennungsgase weniger Stoffe enthalten, die zu einer Umweltbelastung fuehren koennten. Erfindungsgemaess werden Brennstoffbriketts in Gegenwart von synthetischen organischen Verbindungen als Bindemittel sowie einem weiteren Zusatzmittel, in der Weise hergestellt, dass man einem im wesentlichen festen Brennstoff, Polyvinylalkohol und Calciumoxid und/oder Magnesiumoxid in Gegenwart von mindestens 1,0 Gewichtsprozent Wasser miteinander vermischt und in an sich bekannter Weise durch Pressen zu Briketts formt. Das Calciumoxid kann in Form von Branntkalk verwendet werden. Vorzugsweise werden 0,5 bis 4,5, insbesondere 1 bis 3 Gewichtsprozent Calciumoxid, bezogen auf das Trockengewicht des festen Brennstoffs, verwendet. Polyvinylalkohol wird zweckmaessig in Menge von 0,5 bis 2 Gewichtsprozent, berechnet als Trockensubstanz und bezogen auf den festen Brennstoff, eingesetzt. Der Polyvinylalkohol kann in waessriger Loesung verwendet werden, wobei eine 15 bis 18%ige waessrige Loesung bevorzugt ist.
Patent DD-219809-A5 (DD)
Title: Gleisbaumaschine, deren fahrgestell mit einer vorrichtung zum heben und richten eines gleises ausgeruestet ist
Inventor: HURNI HANS
IPC: E01B33/06
Filed: 1984-05-17
Abstract: Die Erfindung betrifft eine Gleisbaumaschine zum Heben und Richten eines Gleises mit dem Ziel, eine betriebssichere und wirtschaftliche Arbeitsweise der Maschine zu ermoeglichen. Aufgabe der Erfindung ist es, eine Gleisbaumaschine zu schaffen, deren Abstand zwischen den Wirkungszonen der Heberollen und des Hebehakens jeder Schiene eines Gleises auf ein Minimum zu reduzieren und durch einfache Konstruktion den Austausch jeder Werkzeuge ermoeglicht und den Betrieb der Maschine mit einem einzigen Werkzeugtraeger und/oder mit zwei uebereinanderliegenden Werkzeugtraegern gestattet. Erfindungsgemaess wird die Aufgabe dadurch geloest, dass der Hebehaken (11) und die Heberolle (12) jeder Schiene hoehenverstellbar auf einem gemeinsamen Tragglied (28; 47; 49; 51; 55; 58; 68; 77; 81) montiert sind und dass dieses gemeinsame Tragglied (28; 47; 49; 51; 55; 58; 68; 77; 81) mindestens quer zum Gleis (5) bewegbar am Werkzeugtraeger (9; 10) fuer die beiden Hebewerkzeuge angeordnet ist. Fig. 2
Patent DD-236732-A5 (DD)
Title: Verfahren zur herstellung von cyclischen imidatesteranamin-zwischenprodukten
Inventor: POINDEXTER GRAHAM S
IPC: C07D265/08
Filed: 1983-05-30
Abstract: Die Erfindung betrifft ein Verfahren zur Herstellung von cyclischen Imidatesterenamin-Zwischenprodukten der allgemeinen Formel II, worinR, R1, R2, R5, m und n die angegebenen Bedeutungen besitzen. Diese Zwischenprodukte koennen zu Endprodukten der allgemeinen Formel I weiterverarbeitet werden. Letztere Verbindungen sind vasodilatatorische Mittel und zur Behandlung von Hypertonie und Ischaemie brauchbar. Formel II, I
Patent DD-232260-A5 (DD)
Inventor: HOSZTAFI SANDOR
IPC: C07C227/26
Filed: 1985-03-11
Abstract: The invention relates to a process for the preparation of DL-β-aryl-amino acids of the general Formula.whereinR,R, and R<sub>2</sub> stand for hydrogen, halogen, C<sub>1-6</sub> alkyl, C<sub>1-6</sub> alkoxy, nitro or C<sub>1-4</sub> dialkylamino.An aqueous solution of glycine and an excess of urea is heated and the reaction mixture is subjected to acidic cyclisation. The hydantoin thus obtained is reached with an aromatic aldehyde of the general Formulain aqueous solution in the presence of an excess of ethanolamine or morpholine. The 5-arylidene hydantoin derivative of the general Formulathus obtained is reduced quantitatively in a dilute alkaline medium with a Raney-nickel or a palladium-carbon catalyst to yield the corresponding 5-aryl-methyl-hydantoin derivative of the general Formula R which is subjected to alkaline hydrolysis. The corresponding DL-β-aryl amino acid of the general Formula V is obtained in high yield and may be isolated at the isoelectric point thereof
Patent DD-283541-A5 (DD)
Title: Verfahren zur sterilisation der staubbeutel von pflanzen
Inventor: FEDIN MARAT A
IPC: A01N31/00
Filed: 1988-12-12
Abstract: Die Erfindung betrifft ein Verfahren zur Sterilisation der Staubbeutel von Pflanzen, welches es ermoeglicht, Staubbeutel eines breiten Spektrums von Kulturen mit hohem Sterilisationsgrad unter Erhaltung der Faehigkeit von Samen, Furchtansaetze bei freier Bestaeubung zu bilden, zu sterilisieren. Im erfindungsgemaeszen Verfahren werden die Pflanzen mit einem Sterilisationsmittel, das einen Verduenner enthaelt, in der fuenften und/oder sechsten Periode der Organogenese behandelt. Als Wirkstoffe im Sterilisationsmittel verwendet man erfindungsgemaesz Derivate von aliphatischen Alkoholen der allgemeinen Formel, worin die Substituenten R1, R2, R3, R4 und Y die in der Beschreibung angegebene Bedeutung haben. Das erfindungsgemaesze Verfahren wird in der Landwirtschaft in der Selektion und im Samenbau verwendet. Formel{Staubbeutel-Pflanzen; Sterilisationsverfahren; Sterilisationsmittel; Wirkstoff aliphatische Alkohole; Landwirtschaft, Selektion; Samenbau}
Patent DD-280557-A5 (DD)
Inventor: KLOS KLAUS-PETER
IPC: C23C22/34
Filed: 1989-04-10
Abstract: An acidic chromium(III)-containing and fluoride-containing passivating bath for surfaces of zinc, zinc alloys and cadmium is prepared by mixing 20-200 g/l of a soluble chromium(III) compound, 20 to 600 g/l of a soluble nitrate, 5 to 100 g/l of a fluoride and of a sulphate, phosphate, chloride, bromide, fluoride or iodide anion, adding hydrochloric or nitric acid to a pH of 1.8 to 2.2 and heating to above 60 DEG C or adding a catalyst, the amount of nitrate being greater than the chromium(III) concentration. It contains one or more complex(es) of the formula (1): <IMAGE> (x = 1 to 3, n = valency of A and A = nitrate, sulphate, phosphate, chloride, bromide, fluoride or iodide).