Ferrous chloride sulphide

Due to its symmetrical structure, pentaerythritol tetranitrate is characterized by high resistance to many reagents. Thus PETN, differing from the majority of nitric esters, is not readily decomposed by sodium sulphide at 50°C. On the other hand, it is decomposed quite quickly by boiling in a ferrous chloride solution. Boiling with a 2.5% solution of sodium hydroxide causes very slow decomposition, whereas nitrocellulose rapidly decomposes under these conditions. 

Oxychloride. — The solution of 1 gm. of ferrous chloride in 1 cc. of water and 2 to 3 drops of hydrochloric acid should be pale green or green in color, and should not have any yellowish-green tint. On adding 5 cc. of saturated hydrogen sulphide water, the solution should show only a very slight turbidity, due to the separation of sulphur ... 

Sulphur alone has no action upon platinum,3 but metallic sulphides are liable to attack it. Phosphorus, phosphides, and phosphates under reducing conditions attack the metal, so that these and the aforesaid sulpirides should not be ignited in platinum crucibles in quantitative analysis. Ferric chloride solution is reduced to ferrous chloride when evaporated in a platinum dish, platinum passing into solution. 

A solution of ferric chloride decomposes lead sulphide or powdered galpna with ease on warming, the products being ferrous chloride, lead chloride, and sulphur.2... 

A precipitate of ferric sulphide is also obtained when ammonium sulphide is added to a solution of a ferric salt, the alkali remaining in excess.4 If, however, the ferric salt is present in excess, the precipitate appears to consist of a mixture of ferrous sulphide and free sulphur. As obtained by either of the foregoing methods, the sulphide is hydrated and unstable in air. Dilute hydrochloric acid decomposes it completely into ferrous chloride, with evolution of hydrogen sulphide and a simultaneous deposition of sulphur. When boiled with water it yields ferric hydroxide and hydrogen sulphide. 

Pyrrhotite has been prepared7 artificially by heating ferrous chloride and sodium carbonate with water in a rifle-barrel at 200° C. for 16 days in an atmosphere of hydrogen sulphide and carbon dioxide. The reaction proceeds easily between 80° and 225° C.8 at the lower temperature, yielding hexagonal crystals, and at the higher temperature rhombic ones. 

Artificial pyrrhotite has also been obtained by passing hydrogen sulphide over heated ferrous chloride, air having been previously expelled by passage of carbon dioxide9 and by decomposing marcasite or iron pyrites with hydrogen sulphide at temperatures above 575° C.8 The reaction may be first detected at about this temperature and proceeds fairly rapidly at 665° C. The mineral is not a definite compound, but in all probability a solid solution of sulphur m iron sulphide.10... 

Iron monophosphide, FeP, results when vaporised phosphorus is passed over diferro phosphide at red heat, until no further increase in weight occurs.3 It has also been prepared by heating phosphorus and iron together at red heat,4 and also by the action of hydrogen phosphide upon ferric chloride,5 ferrous sulphide,6 or ferrous chloride 7 at red heat. 

Steels and stainless steels show preferential nucleation of pits at inclusions, most notably sulphide inclusions ". Other sulphur-rich regions in ferrous and nickel-based alloys may also lead to premature failure. It has been shown that accumulation of sulphur on the surface of these materials retards passivity and enhances dissolution of the metal. These effects occur in any solution in which the metal shows an active region and they are also preferential pitting sites in the presence of chloride. A recent notion for... 

Estimation of Selenium in Sulphide Minerals.s—In various sulphite-cellulose manufactories difficulties have occurred which have been traced to the presence of selenium in the pyrites used for burning. Part of the selenium remains in the burnt pyrites and part volatilises with the sulphur dioxide. 20 to 30 grams of pyrites are dissolved in hydrochloric acid (dens.=1-19) and potassium chlorate. Zinc is added to reduce the iron to the ferrous condition more hydrochloric acid is then added, the solution boiled and stannous chloride added to precipitate selenium. Since the selenium may contain arsenic, it is collected on an asbestos filter, dissolved in potassium cyanide and reprecipitated using hydrogen chloride and sulphur dioxide. The element may then be estimated by the iodometric method described below. In order to determine the relative proportion of volatile to non-volatile selenium, the pyrites may be roasted in a current of oxygen. After this treatment the contents of the tube are dissolved in warm potassium cyanide and the selenium reprecipitated and estimated in the ordinary way. 

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