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It will have been noticed that one of the chief reagents in the Leblanc process is the sulphur used in the form of brimstone or as pyrites for making vitriol in the first stage; this sulphur goes through the entire process; from the vitriol it goes to form a constituent of the salt-cake, and afterwards of the calcium sulphide contained in the black ash.
A convenient apparatus for the preparation of hydrogen sulphide from coal-gas, such as we have at present in use in the Christ College laboratory, consists of a retort, R, in which sulphur is placed. Through the tubulure of the retort there passes a bent glass-tube, T E, perforated near the closed end, F, with a number of small holes.
In the determination of sulphur in steel by evolving the sulphur as hydrogen sulphide, precipitating cadmium sulphide by passing the liberated hydrogen sulphide through ammoniacal cadmium chloride solution, and decomposing the CdS with acid in the presence of a measured amount of standard iodine, the following data are obtained: Sample, 5.027 grams; cc. Na S O sol. = 12.68; cc.
The filtrate and washings should always be carefully examined for minute quantities of the sulphate which may pass through the pores of the filter. Subsequent ignition, with ready access of air, reconverts the sulphide to sulphate unless a considerable reduction has occurred. PROCEDURE. Weigh out, into platinum crucibles, two portions of about 0.5 gram of the sulphate.
Hæmochromogen gives a very characteristic spectrum, and is obtained by reducing alkaline hæmatin by ammonium sulphide. Carbon monoxide hæmoglobin gives a spectrum which resembles that of oxyhæmoglobin, but it is not reduced by ammonium sulphide.
The iron in water from old coal pits and shale deposits is usually present as sulphate due to the oxidation of pyrites, a sulphuret or sulphide of iron. Water from heaths and moorlands is often acid from certain vegetable acids termed "peaty acids." This acidity places the water in the condition of a direct solvent for iron, and that dissolved iron may cause great injury.
In places, however, it is warm, for when the oxygen of the air reaches the fresh sulphide it begins to oxidize the ore; that is, it begins to burn it, and change it into a different compound, just as fire changes wood or coal. Wherever oxidation is going on, heat is produced. Fresh air is constantly needed in these workings far underground.
The ore from which the metal was extracted is called chalcitis by Pliny, and may have been the "chalcocite" of our present metallurgical science, which is a sulphide containing very nearly eighty per cent. of copper. The brief account which Strabo gives of the mines of Tamasus shows that the ore was smelted in furnaces which were heated by wood fires.
The trouble is chicken pox, which is a very contagious disease. A treatment which has been successful consists in bathing the sores with strong salt and water and giving the fowls a mash containing one teaspoonful of calcium sulphide for each 25 hens.
Now on taking a little cotton and heating with the caustic alkaline lead solution, if sulphur were present in that cotton, the fibre would turn black or brown, for the lead would at once absorb such sulphur, and form in the fibre soaked with it, black sulphide of lead. No such coloration is formed, so cotton does not contain sulphur. Secondly, we must test silk.
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