Chromium salts Subject

Preservative formulations that contain copper and chromium salts reportedly promote afterglow in treated wood subjected to fire. Once the treated wood starts to burn or glow, the wood may continue to glow until the entire member is consumed, even when no flame is present (38, 39). This characteristic can cause serious problems in utility poles, fenceposts, and highway signs, structures that might be... 

As already stated, the polyphenols are firmly bormd to the collagen in leathers which have been subjected to vegetable tanning. In the TFG of a leather sample we may therefore expect that this bond will be broken and that fragmentation of both the tannin and the collagen will occur. Fig. 10 ows the TFG of an animal in treated only with chromium salts (chrome-tanned leather). For comparison. Fig. 11 pves the TFG of a chrome leather that has been further tanned with mimosa extract the characteristic, prominent zones of resorcinol (3) and pyrocatechol (2) show up clearly. The typical products of thermolysis of vegetable tanned and unfinished leathers are compiled in Table 5. 

Ductile and easily buffed chromium deposits having satisfactory corrosion resistance have been produced thus 0.005 mm-thick chromium deposits applied to steel by chemical deposition or by eiectrodeposition gave simiiar results when subjected to a salt-spray test . 

This reaction is subject to a number of errors (1) the hydriodic acid (from excess of iodide and acid) is readily oxidised by air, especially in the presence of chromium(III) salts, and (2) it is not instantaneous. It is accordingly best to pass a current of carbon dioxide through the reaction flask before and during the titration (a more convenient but less efficient method is to add some solid sodium hydrogencarbonate to the acid solution, and to keep the flask covered as much as possible), and to allow 5 minutes for its completion. 

Chromium has proved effective in counteracting the deleterious effects of cadmium in rats and of vanadium in chickens. High mortality rates and testicular atrophy occurred in rats subjected to an intraperitoneal injection of cadmium salts however, pretreatment with chromium ameliorated these effects (Stacey et al. 1983). The Cr-Cd relationship is not simple. In some cases, cadmium is known to suppress adverse effects induced in Chinese hamster (Cricetus spp.) ovary cells by Cr (Shimada et al. 1998). In southwestern Sweden, there was an 80% decline in chromium burdens in liver of the moose (Alces alces) between 1982 and 1992 from 0.21 to 0.07 mg Cr/kg FW (Frank et al. 1994). During this same period in this locale, moose experienced an unknown disease caused by a secondary copper deficiency due to elevated molybdenum levels as well as chromium deficiency and trace element imbalance (Frank et al. 1994). In chickens (Gallus sp.), 10 mg/kg of dietary chromium counteracted adverse effects on albumin metabolism and egg shell quality induced by 10 mg/kg of vanadium salts (Jensen and Maurice 1980). Additional research on the beneficial aspects of chromium in living resources appears warranted, especially where the organism is subjected to complex mixtures containing chromium and other potentially toxic heavy metals. 

Cobalt. Cobalt was determined colorlmetrically as the nltroso-R salt (13). The use of any nltroso salt comes under scrutiny as a suspected carcinogen. Cobalt can be analyzed at 240.7 nm with an air-acetylene flame this analytical line is subject to line broadening and self-absorption necessitating background correction. The analyst should be aware that greater than 2000 ppm nickel and chromium can be interferences. 

Crude oils — Petroleum in its natural form before it is subjected to any refining process such as fractional distillation or catalytic cracking. The main elements in crude oils are hydrogen and carbon as they are composed of mixtures of hydrocarbon compounds. Crude oils also contain varying amounts of sulphur, nitrogen, oxygen, and sometimes mineral salts, as well as trace metals such as nickel, vanadium, and chromium. 

Potassium or sodium-potassium alloy mixed with ammonium nitrate and ammonium sulfate results in explosion (NFPA 1986). Violent reactions may occur when a metal such as aluminum, magnesium, copper, cadmium, zinc, cobalt, nickel, lead, chromium, bismuth, or antimony in powdered form is mixed with fused ammonium nitrate. An explosion may occur when the mixture above is subjected to shock. A mixture with white phosphorus or sulfur explodes by percussion or shock. It explodes when heated with carbon. Mixture with concentrated acetic acid ignites on warming. Many metal salts, especially the chromates, dichromates, and chlorides, can lower the decomposition temperature of ammonium nitrate. For example, presence of 0.1% CaCb, NH4CI, AICI3, or FeCb can cause explosive decomposition at 175°C (347°F). Also, the presence of acid can further catalyze the decomposition of ammonium nitrate in presence of metal sulfides. 

The same remarks apply to these results as to those given with respect to the sp. gr. at 40° and 50°. G. D. van Cleeff observed that in the dialysis of soln. of the salt the dialyzed part contains more acid than the part which remains this was confirmed by M. D. Dougal, and T. W. Richards and F. Bonnet found that when a violet soln. of chromium sulphate is subjected to dialysis, the ratio Cr/SO of the salt that has diffused and the salt that has remained in the dialyzer is the same in both. When, however, a green soln. of chromium is similarly treated, the ratio Cr/SO diminishes in the diffused portion and increases in the dialyzer— an observation in favour of the view that the change from violet to green involves a hydrolysis with formation of free acid and a soluble basic salt. 

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