SUBJECTS iron 687 sulphate

The slight attack of acid on carbon steel results in the formation of iron sulphate which provides an effective seal against further corrosion unless subjected to weaker acid strengths for prolonged periods. 

Chromium in steel Discussion. The chromium in the steel is oxidised by perchloric acid to the dichromate ion, the colour of which is intensified by iron (III) perchlorate which is itself colourless. The coloured solution is compared with a blank in which the dichromate is reduced with ammonium iron(II) sulphate. The method is not subject to interference by iron or by moderate amounts of alloying elements usually present in steel. 

Lastly, a portion of the infusion of galls was. subjected, to eontinned ebullition, by which meaos part of its contents became iosoluble the menstruum was filtered, and sulphate of iron added to. the filtrate, pro.-ducing a good and permanent ink. 

Tha Dublin college at first prepares the sulphate of mercury, and intimately mixes this in fine powder with dried common salt, likewise ground, in the proportion. of two of the former to one of the latter, subjecting the mixture to heat in an iron pot lined with clay, to which an oarthen head is adapted. In either of these operations the temperature at which the salt is sublimed should not he too elevated, as in this case the ohloride would fuse and fall hock into the yeBsd, and thus occasion a loss.. . ... 

Further restrictions to the scope of the present article concern certain molecules which can in one or more of their canonical forms be represented as carbenes, e.g. carbon monoxide such stable molecules, which do not normally show carbenoid reactivity, will not be considered. Nor will there be any discussion of so-called transition metal-carbene complexes (see, for example, Fischer and Maasbol, 1964 Mills and Redhouse, 1968 Fischer and Riedel, 1968). Carbenes in these complexes appear to be analogous to carbon monoxide in transition-metal carbonyls. Carbenoid reactivity has been observed only in the case of certain iridium (Mango and Dvoretzky, 1966) and iron complexes (Jolly and Pettit, 1966), but detailed examination of the nature of the actual reactive intermediate, that is to say, whether the complexes react as such or first decompose to give free carbenes, has not yet been reported. A chromium-carbene complex has been suggested as a transient intermediate in the reduction of gfem-dihalides by chromium(II) sulphate because of structural effects on the reaction rate and because of the structure of the reaction products, particularly in the presence of unsaturated compounds (Castro and Kray, 1966). The subject of carbene-metal complexes reappears in Section IIIB. 

Nitroso derivatives of a more complex and more stable character than the foregoing were discovered by Roussin in 1858.2 This investigator observed that a black voluminous precipitate is obtained when a mixture of ammonium sulphide and alkali nitrite is added to an aqueous solution of ferrous sulphate. On boiling, the precipitate passes into solution. The liquid is filtered, and, upon cooling, black crystals separate out, the composition of which has been the subject of considerable discussion. The reaction does not proceed in perfectly neutral solution, a green liquor only being produced, consisting of sulphides of iron and sodium, entirely free from any nitroso derivative. The presence of a small quantity of acid, however, results in the formation of the nitroso derivative, probably because it liberates nitrous acid, which acts direct upon the ferrous salt. 

Bastnasite is mined from hard rock deposits. Production in China is a by-product of iron ore mining while U.S, production is solely for rare-earths. Ore is recovered by drilling and blasting. The ore Is crushed, ground and subjected to flotation. The bastnasite fraction is floated off and thereby seperated from other minerals to produce a concentrate. Bastnasite can be converted directly, without separating individual rare-earths, to other derivatives such as sulphate or chloride by dissolution in acid. The following step to crack the concentrate for further processing used in the U.S. is to roast in air and then to leach with HCl. This produces an insoluble cerium rich... 

Two thienyl rings joined at various positions and having a formyl group attached to one ring and a nitro to the other undergo cyclization when subjected to partial reduction with iron(II) sulphate and ammonia. 

Cowper-Coles found that a soln. of 100 parts of chrome-alum in 100 parts of water with 12 parts of barium sulphate does not yield a deposit of chromium metal on electrolysis. E. Placet found that when a soln. of chrome-alum and an alkali sulphate acidified with sulphuric acid, is electrolyzed, chromium is deposited at the cathode as a hard, bluish-white, lustrous metal, which, under certain conditions, crystallizes in groups resembling the branching of firs. Other metals and alloys— bronze, copper, iron, brass, etc.—may be plated with chromium, and a surface can be obtained to resemble oxidized silver. E. Placet and J. Bonnet have a number of patents on this subject. 

Dissolve the sulphate of iron and the carbonate of ammonia separately in half a gallon of the water, and mix the two solutions with brisk stirring in a deep cylindrical vessel, which is then to be covered as accurately as possible. Set the mixture by for twenty-four hours, and from the precipitate (carbonate of iron) which has subsided separate the supernatant liquid by a siphon. Pour on the remainder of the water, stir well, and after subsidence again remove the clear liquid. Collect the resulting carbonate on a calico filter, and, having first subjected it to expression, rub it with the sugar in a porcelain mortar. Finally, dry the mixture at a temperature not exceeding 212 F. 

Weast et al. (1961) contributed to this subject by measuring electrode potentials of zinc and steel in aqueous systems under pressure according to the procedure of Hoxeng and Prutton. It was found that 3 atm of oxygen pressure with saturated CaCOs + sulphate or chloride made zinc more notable (0.50-0.65 V, vs. 0.88 V at atmospheric pressure with iron usually 0.6-0.7 V). 

The iron-carbon system has been investigated in our laboratory. The powders were subjected to thermal treatment and next they were investigated by the potentiometric method in powder electrodes, and by the metallographic method using grinds and corrosions of the powder in shellac. Both the carbon content and the structure of the system had an influence on the rates of change and the value of the powder electrode potential in aqueous solution of potassium sulphate. The potentiometric measurements enabled us to define the structure when the quantitative composition of an alloy was known. 

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