Abstract: Bismuth vanadate pigments IBi.sub.x Fe.sub.y E.sub.v V.sub.(1-w) P.sub.w O.sub.z Iwith the following meanings of the variables:E denotes calcium, zinc, cerium, praseodymium, and/or silicon;x is a value from 0.8 to 1.2;y is greater than 0 to 0.1 when v is greater than 0 or is greater than or equal to 0.035 to 0.1 when v is equal to 0;v is greater than or equal to 0 to 0.2;w is greater than 0 to 0.1;z denotes the number of oxygen atoms required to satisfy the valence requirements of the cations.and the preparation and use of said pigments for dyeing coating compositions, printing inks, and plastics.

Abstract: A process for preparing transparent yellow iron oxide pigments by the precipitation of iron (II) hydroxide by adding an inorganic base to an iron (II) salt solution and subsequent oxidation to FeOOH.

Abstract: In laked tris- or tetracationic polymethine dyes I ##STR1## the variables have the following meanings: A is the radical of a fused-on substituted or unsubstituted benzene or naphthalene nucleus,Y is nitrogen or phosphorus,Z is --NR.sup.1 --, --O--, --S--, --C(CH.sub.3).sub.2 -- or --CH.dbd.CH--, where R.sup.1 is a radical as defined for R,D is --CX.sup.1 .dbd., --CH.dbd.CX.sup.1 --CH.dbd., ##STR2## Het.sup.e is the equivalent of a heteropolyacid anion, m is from 1 to 10, andn is 3 or 4, where (R).sub.3, X.sup.1, and X.sup.2 have the meanings set out in the specification.

Abstract: An essentially monoclinic bismuth vanadate of the formula Bi[V.sub.1-x P.sub.x)O.sub.4 ] where x is from 0 to 0.1 has a chroma of .gtoreq.85, a lightness of .gtoreq.80, a hue angle of from 89 to 95 and a photochromism with a .DELTA.E value of .ltoreq.2 under the CIELAB system.

Abstract: Thermostable bismuth vanadate/molybdate pigments are prepared by precipitating onto a pigment, obtained by calcination, of the formulaBi VO.sub.4 .cndot.Bi.sub.2 Mo O.sub.6where n is 0.2-2.5, in aqueous suspension at 70.degree.-100.degree. C. within the pH range from 4 to 9.5 a first SiO.sub.2 -containing layer using an alkali metal silicate solution of a magnesium hexafluorosilicate solution, maintaining the suspension at 70.degree.-100.degree. C. for not less than 1 hour, producing a thick coating on the precoated pigment by adding further alkali metal silicate solution, magnesium hexafluorosilicate solution or a mixture of the two within the pH range from 4 to 9.5, and finally depositing wax on the SiO.sub.2 -containing layer by means of a waxing emulsion/dispersion, the products showing, compared with the starting pigment, an appreciably improved thermal stability in plastics.

Abstract: Magnetite pigments are prepared from iron(II) salt solutions by a process in which the mean particle size can be brought to a value within the range from 0.06 to 0.5 .mu.m by means of a residence stage between the precipitation stage and the oxidation stage.

Abstract: The invention relates to basic chromium aluminum sulfates which are soluble in cold water and are of the general formulaCr.sub.x Al.sub.2-x (OH).sub.2 y. (SO.sub.4).sub.3-y.n H.sub.2 Owhere x is from 0.1 to 1.9, y is from 0.01 to 2 and n is from 4 to 24, and a process for the preparation thereof. The process comprises reacting chromium (III)--containing waste sulfuric acid having a water content of 20-50% by weight with aluminum oxide and/or aluminum oxide hydroxide and/or aluminum hydroxide at a temperature of 100.degree. to 200.degree. C. The molten product is converted to droplet form and allowed to solidify in free fall.

Abstract: Thermally stable lead chromate pigments or pigments containing lead chromate, which have high color strength and are provided with a precipitated coating containing silicon dioxide, are prepared by a process in which an aqueous pigment suspension is mixed once or several times with an aqueous MgSiF.sub.6 solution, the pH being maintained at 4.5-9.5 and the temperature at 50.degree.-95.degree. C., and the pigment is then separated off and worked up, these steps being carried out in a conventional manner.

Abstract: Yellow pigments containing bismuth vanadate and having the compositionBiVO.sub.4.xBi.sub.2 MoO.sub.6.yBi.sub.2 WO.sub.6where x is from 0.6 to 2.25 and y is from 0 to 0.1, are prepared by a process in which a solution containing a bismuth(III) salt, a vanadate and a molybdate is acidified until the pH is <0, the pH of the acidic solution is then brought to 0.1-3.5, at from 20.degree. to 95.degree. C., by means of an alkaline solution which may or may not contain a dissolved tungsten(VI) compound, the precipitated product and the reaction solution are left at from 50.degree. to 100.degree. C. for from 30 to 120 minutes and then separated from one another, and the product is washed, dried if required and heated at from 300.degree. to 800.degree. C.