Blue chromate

CA 55, 25259(196 l)(Combustion catalysts for AN comp proplnts include Prussian blues, chromates Na barbiturate in quantities of 2-6% of total proplnt) 12)W.G, Stanley W.G. Proell, USP 2988437(1961) CA 55, 25258 (1961)(Combustion caralysts for AN comp proplnts include scable metallic cyan amides of Ba, Cu, Pb, Hg or Ag or their mixts in amts 2-4% of total proplnt)... 

Blue chromating. Two typical bath compositions are given in Table 20. 

The layers have a more or less blue color depending on the thickness of the film. The thickness of the layer should be 50 to 90 nm, however exact control of the layer thickness is difficult. The corrosion protection of a blue chromating film is very limited. 

Formation of chromium films containing only chromium(lll) A first example was the blue chromating films without chromium(VI). But these films are too thin and reveal only limited corrosion protection. 

Addition of hydrogen peroxide to a solution of a dichromate yields the blue colour of "peroxochromic acid. This is a test for soluble chromates and dichromates. 

Hydrogen peroxide with a chromate or a dichromate gives a blue colour. 

Chemical Properties. The valence states of chromium are +2, +3, and +6, the latter two being the most common. The +2 and +3 states are basic, whereas the +6 is acidic, forming ions of the type CrO (chromates) and (Cr203 [ (dichromates). The blue—white metal is refractory and very hard. 

Other Color Order Systems. The Natural Color System (24), abbreviated NCS, developed ia Sweden is an outgrowth of the Hesselgren Color Adas, and uses the opponent color approach. Here colors are described on the basis of their resemblances to the basic color pairs red-green and blue-yeUow, and the amounts of black and white present, all evaluated as percentages. Consider a color that has 10% whiteness, 50% blackness, 20% yellowness, and 20% redness note that the sum is 100%. The overall NCS designation of this color is 50, 40, Y50R iadicating ia sequence the blackness, the chromaticness (20 + 20), and the hue (50% on the way from yellow to red the sequence used is Y, R, G, B, Y). 

Harmine, C13H12ON2, crystallises from methyl alcohol in colourless rhombic prisms, m.p, 266°, [a]D 0°. The hydrochloride, m.p. 269-5-270-5° (Chen ), nitrate, platinichloride, m.p. 264-6°, acid chromate and oxalate crystallise well. The salts show a deep blue fluorescence in dilute solution. Harmine behaves as a monoacidic base. It gives a methiodide, from which methylharmine, needles, m.p. 209°, may be prepared, and this in turn yields methylharmine methiodide. On demethylation harmine yields the phenolic base harmol, C12H10ON2, m.p. 321°.i ... 

Table 1 Comparison of the reaction of pesticides (amounts applied 0.8 pg, without chromat graphic development) with N,N-DPDD (Wurster s Red) and TPDD (Wurster s Blue) reager [4] - = negative, (+) = weakly positive and + + + = positive reaction.

If we have a certain color, a change in intensity has a major effect on what we see (in both reflectance and emittance). For example, if we have a blue, at low intensity we see a bluish-black, while at high intensity we see a bluish-white. Yet, the hue has not changed, only the intensity. This effect is particularly significant in reflectance since we can have a "light-blue" and a "dark-blue", without a change in chromaticity coordinates. 

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