Browning oxidizing

Cadmium is a soft metal, which forms a protective coating in air, and burns only on strong heating to give the brown oxide CdO. It dissolves in acids with evolution of hydrogen ... 

Brown crepes Brown dyes Brownian particles Brown oxides... 

Reduction to Metal Powder. The metal powder is obtained from APT by stepwise reduction with carbon or hydrogen. The intermediate products are the yeUow oxide, WO blue oxide, (see Tungsten compounds) and brown oxide, WO2. Because carbon introduces impurities,... 

Tungsten dioxide [12036-22-5] WO2, is a brown powder formed by the reduction of WO3 with hydrogen at 575—600°C. Generally, this oxide is obtained as an intermediate in the hydrogen reduction of the trioxide to the metal. On reduction, first a blue oxide, then a brown oxide (WO2), is formed. The composition of the blue oxide was in doubt for a long time. However, it has since been resolved that W2Q03g and W are formed as intermediates, which may also be prepared by the reaction of tungsten with WO3. 

Brown oxides are manufactured either by blending mixtures of the red, yellow, and black oxides or by precipitation of an iron salt with alkaU followed by partial oxidation of the precipitate. The result is a mixture of red Fe202 [1309-37-1] and black Fe O [1309-38-2] FeO Fe202-... 

The entire internal surface was covered with a layer of dark greasy deposit and slime intermixed with reddish-brown oxides (oxides were dark immediately upon removal from systems) (Figs. 3.19 and 3.20). Analysis showed tubercular contents were fairly acidic. 

The brown oxide is a heavy granular powder which settles to the bottom of the solution in the bottle in which the reduction is carried out (p. 10). It must be reduced to platinum black before it becomes a catalyst for the reduction. When the hydrogen is admitted and the bottle shaken the brown oxide becomes black and whips up into a fine suspension. The time necessary for the change of the oxide to platinum black is called the lag. The time of lag varies usually from several seconds to two or three minutes, depending upon the conditions under which... 

To the solid in a 3-1. Erlenmeyer flask is added 270 ml. of water, then 90 g. (65 ml., 1.0 mole) of concentrated nitric acid slowly (Hood ). The contents of the flask are swirled and allowed to stand until frothing and evolution of reddish brown oxides of nitrogen subsides. Dow-Coming Antifoam A helps to control frothing. 

Burnishing is the formation of black-brown oxide films on iron and its alloys by controlled oxidation of cleaned metal surfaces. These films are extremely complex and contain, in addition to maghemite and magnetite (or a substituted magnetite for Ni, Mo or Co alloys), various nitride phases - Fe4N, FeaN and FeN. The nitride phases are adjacent to the metal and the iron oxides are in the outer layers of the film (Gebhardt, 1973). 

Yellow-brown oxide called tribromide of niobium, NbOBrs [14459-75-7], is produced by reacting niobium pentoxide with bromine and carbon at 550°C ... 

The preceding method is applicable to any of the ordinary classes of iron ore, such as the hematite, brown oxide, magnetic, cetera. Sulphides are never used for the manufacture of the metal hut even these, such as the common pyrites, may also he tested in the same way,... 

The reaction between tetraethylthiuram disulfide with the Ni(EtXant)2 complex gives a red-brown oxidation product with an EPR spectrum consisting of one line and has an isotropicg value of 2.106 (at low temperatures). At room temperature this product is rapidly converted into Ni(Et2Dtc)2. The composition Ni(IllXEtXantXEt2Dtc)+ was suggested for this product (75). 

The brown oxidized solution is filtered and allowed to evaporate spontaneously for at least five days in several large crystallizing dishes in layers of liquid about one inch deep. After this time, huge brown crystals of product have formed as well as a fine orange-yellow contaminating crystalline powder ... 

In addition to the tungsten(II) bonde mentioned above, the element forms at least two other borides, W2B and WB2 it forms a similar series of phosphides, W2P, WP, and WP2 as well as W02 (brown oxide), W4On (blue oxide), and WO3 (yellow oxide), and two sulfides, WS2 and WS3. The tungsleu(IV) oxide and sulfide are representative uf the simple Lelravalent compounds, which also include a tetrabromide, WBr4, and tetraiodide, WI4. Like lire drhalides, these tetiahalides undergo hydrolysis quite readily. 

Reddish brown precipitate of silver chromate Yellow precipitate of silver iodide Black precipitate of silver sulfide Yellow precipitate of silver phosphate Yellow-white precipitate of silver carbonate, forming a brown oxide upon heating... 

Adams Platinum Oxide (by Adams et a/.).148 In a porcelain casserole is prepared a solution of 3.5 g of chloroplatinic acid in 10 ml of water, and to this is added 35 g of sodium nitrate.The mixture is evaporated to dryness while stirring with a glass rod. The temperature is then raised to 350-370°C within 10 min. Fusion takes place, brown oxides of nitrogen are evolved, and a precipitate of brown platinum oxide gradually separates. After 15 min, when the temperature has reached about 400°C, the evolution of gas has gently decreased. After 20 min the temperature should be 500-550°C. The temperature is held until about 30 min have elapsed, when the fusion should be complete. The mass is allowed to cool and is then treated with 50 ml of water.The brown precipitate settles to the bottom and can be washed by decantation once or twice, then filtered, and washed until practically free from nitrates. If the precipitate becomes colloidal, it is better to stop washing immediately at that stage. The oxide is either used directly or dried in a desiccator. The yield is 1.57-1.65 g (95-100% of the theoretical amount). 

Mixtures for Matches, For sulphur dips Phosphorus, 3 parts glue, 5 parts sand, 1 part incorporated below 100° Fahr., with 10 parts of water. Or, phosphorus, 5 parts fine sand, 4 parts red ochre, 1 part (or, ultramarine), part gum-arabic, 5 parts, in 6 pints of water (or, 4 parts of glue in 9 parts of water). For etearine dips Phosphorus, 3 parts brown oxide of lead, 2 parts turpentine, i part, softened in 3 parts water. Instead of the brown oxide, 2 parts of red lead stirred up with i part of nitno acid mar bo used. 

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