Sulphuretted hydrogen

Hydrosulphuric Acid.—This compound is formed when hydrogen and sulphur come in contact in the nascent state. It is best prepared by causing diluted hydrochloric or sulphuric acid to act on sulphuret of iron in the apparatus, p. 46, when sulphuretted hydrogen is disengaged as a gas, which may be collected over warm water, or solution of sSt. The action is as follows Fe S -f H Cl = Fe Cl -b HS. 

This gas is combustible, burning with a bluish flame, and producing sulphurous acid gas and water. Its Sp. G. is 1 177. Water absorbs 2 or 3 times its volume of the gas, and acquires its smell and a nauseous sweetish taste. By contact with the air, the solution is gradually decomposed water is formed and sulphur deposited. Sulphuretted hydrogen water must, therefore, be kept in small phials, quite full and closely stopped. 

This compound is formed when alkalies, such as potash or lime, are boiled with excess of sulphur, and the solution, which is of a deep yellow or orange colour, is poured into a large excess of moderately strong hydrochloric acid, made by mixing eqrtal parts of concentrated acid and water. A heavy, somewhat viscid, transparent, yellowish liquid fells to the bottom, which is the compound in question. The precise nature of all the changes which take place in this process is not known but it is probable that a persMphuret of the metal is formed in the first 

When chloride of sulphur, SCI, acts on dry ammonia, NH, a compound is formed, SCI, 2 NH,. By the action of water on this there is formed, among other products, a greenish yellow solid body, which is sulphuret of nitrogen NS,. By contact with water, it is gradually converted into hyposulphurous acid and ammonia for 2 NS, + 6 H 0 = 2 NH, -f 3 S, 0,. (Soubeiran). 

When aqua ammoni acts on chloride of sulphur, a variety of products are formed, among which is one, a white crystallisable solid, soluble in alcohol, which appears to consist chiefly of sulphur and nitrogen. Its nature is not yet ascertained, but it is distinguished by the property of dissolving in an alcoholic solution of potash with a deep purple colour, which soon disappears, while ammonia is given off, and cryshils of hyposulphite of potash are deposited—(W. G.) 

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The phenylhydrazone melts at 109° to 110°, and the semi-carbazone at 162° to 163° (active varieties) or 154° to 155° (inactive form). The sulphuretted hydrogen compound mentioned above melts at 210° to 211°. 

The resulting gas, which is known as " sulphuretted hydrogen, has a characteristic and extremely unpleasant odour, and is poisonous when inhaled. According to Th6iard, respiration in an atmosphere containing gihy part of its volume of sulphuretted hydrogen is fatal to a dog, and smaller animals die when half that quantity is present. 

Sulphuretted hydrogen is an inflammable gas, and will burn in air, in accordance with the following equa-ion —... 

Sulphuretted hydrogen is soluble in water at 0° C. 0 the extent of 4 37o6 parts by volume per unit volume )f water. 

Selenuretted hydrogen is inflammable and burns in le same way as sulphuretted hydrogen. If the gas is rongly heated it breaks up into its two constituents, le selenium being deposited in the crystalline form. 

The hydrogen produced by this process would be liable to contain traces of methane, arsine, and sulphuretted hydrogen, the amount depending on the purity of the coal used. 

Removal of Sulphuretted Hydrogen,—For most purposes for which water gas is required it is desirable that it should be free from sulphuretted hydrogen, this is usually accomplished by passing the gas at about 55°-65° F. over hydrated oxide of iron, when the following reaction takes place —... 

After lapse of time, the hydrated ferric oxide ceases to have any sulphuretted hydrogen-absorbing power, so the gas is diverted through other hydrated oxide, and the spent oxide removed and placed in the open air, when, after moistening with water and exposure, the following reaction takes place.—... 

Thus it is seen the original oxide can be reproduced, and on reproduction can be used for the absorption of fresh sulphuretted hydrogen. In practice each revivification increases the free sulphur content of the oxide... 

In this country, it is not generally necessary to heat e hydrated oxide of iron tiirough which the crude ater gas is passed, as the heat evolved by the chemical action is sufficient to keep the oxide at a suitable tem- rature. However, in many parts of the world, where e winter temperature is exceedingly low, it is neces-ry to pass steam coils through the oxide, as otherwise ) absorption of sulphuretted hydrogen takes place. 

The hydrogen is then passed through boxes containing slaked lime, where both the carbon dioxide and sulphuretted hydrogen are absorbed in accordance with the following equations —... 

Hydrogen Caibon dioside monoxide Sulphuretted hydrogen Nitrogen (by difference)... 

With regard to the sulphuretted hydrogen, which is produced merely from die sulphur originally contained in the ore, this decreases with time ore which when put ill the retorts contained 75 per cent of sulphur, after a year in continuous use contained only o 03 per cent... 

The whole of the sulphur compounds in the blue s are converted into sulphuretted hydrogen and are mpletely absorbed by the high pressure water scrub-... 

The gas thus purified from these constituents now passes to the separator proper the reason for this preliminary removal of some of the constituents of the blue water gas is due to the fact that, in the separation of the carbon monoxide and nitrogen, such low temperatures have to be reached that the water, sulphuretted hydrogen, ind carbon dioxide would be in the solid state, and would, therefore, tend to block up the pipes of the apparatus. 

Carbon monoxide Sulphuretted hydrogen. Organic sulphur compounds... 

From the particulars already stated [said he] I considered it as probable that this Silesian oxide of zinc contained likewise the metal which I had discovered and as it gives with sulphuretted hydrogen a precipitate similar in colour to orpiment, I considered this to be the reason why the oxide was supposed to contain arsenic. Some experiments made upon it fully confirmed this opinion. I have, therefore, informed Mr. Hermann of the circumstance by the post and I shall not fail to give the same information to Medicinal Counsellor Roloff, whose letter I received only the day before yesterday... 

Boric sulphide is readily decomposed by water, giving sulphuretted hydrogen and boric acid —... 

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