Page:The New International Encyclopædia 1st ed. v. 18.djvu/786

SULPHOCYANIC ACID. 684 SULPHUR. phur is thus retained partly in the free state, partly as iron sulphide, and by combination with the ammonium cyanide present yields ammo- nium suljilioci/unatc, which may be dissolved out of the reacting mixture with water. Ammonium sulphocyanate itself may be used for the prepara- tion of hydrazine. Usuallj' it is transformed into the sulphocyanate of copper, from which, in turn, the useful sulphocyanate of barium is obtained by the action of baryta. The suljiho- ci/anale of aluminum, another useful salt of sulphocyanic acid, may be obtained by the action of aluminum sulphate on the sulphocyanate of barium. Most of the sulphocyanates are soluble in water. Hulphocyanate of mercury may be obtained by the action of mercuric nitrate on the sulphocyanate of ammonium. It decomposes on moderate heating, the resulting mass, ex- ternally yellow, but black within, assuming a large size and often a most fantastic shape. This sulphocyanate is the principal ingredient of the well-known toy known as "Pharaoh's ser- pents.' Each serpent consists of a little cone of tinfoil, filled with the salt. On lighting the cone at the apex, there begins to issue from it a thick serpent-like coil, which continues twisting and increasing in length to an extraordinary degree. Like cyanic acid (q.v. ). sulphocyanic acid fur- nishes a simple example of the phenomenon known as tautomerism. The two constitutional formulas corresponding to the acid, as deduced from a study of its two dift'erent series of deriva- tives, are as follows : N = C — S — H and H — N = C = S The two imaginary compounds corresponding to these formulas, but in reality represented by only one acid, are called, respectively, sulpho- cyanic acid and iso-su!phocyanic acid (or thio- cyanic acid and iso-thioeyanic acid). SULPHONAL (CH3)„C(S0,aH5),. A white crystalline compound used as a hypnotic. It is prepared by the action of acetone on mercaptan (q.v.) and the oxidation of the resulting product by permanganate of potassium. It is sparingly soluble in water and alcohol and is best ad- ministered with hot milk. It is employed as a substitute for chloral, over which it has the ad- vantage of exercising no depressing action on the heart. It is, however, a poisonous substance and has been known to produce serious functional disturbances and eruptions on the skin. It is sometimes administered in conjiuiction with a similar comjiound, known as trioual (q.v.). SULPHOVINIC ACID. Same as ethyl hvdrogen sulphate, or ethvl sulphuric acid. C'jHj.H.SO,. See Alcohol. SULPHUR (Lat. sulphur, snilfur, sulphur; possil)!}' connected with Goth, su-ibls, OHG. sn^chal, Ger. Schn-efel, A.S. swefl, sulphur). A non-metallic element that has been known since ancient times. Owing to the fact that it burns readily, it was called hrcnnestone or brimstone, and was regarded by the alchemists as the prin- ciple of combustibility, representing the altera- bility of metals by fire. It occurs in the uneom- bined state, though usually contaminated with clay, bitumen, and other impurities, and some- times with traces of arsenic, selenium, tellurium, etc.. usually in the vicinity of volcanoes and hot springs. Its compounds, especially those with metals fsulphides). are of common occurrence, and include chalcopyrite or copper-iron sulphide, cinnabar or mercury sulphide, galena or lead sulphide, pyrite or iron sulphide, the arsenic sulphides or realgar and orpiment, sphalerite or zinc sulphide, stibnite or antimony sulphide. In combination with metals and oxygen (sulphates), sulphur occurs in such minerals as anglesite or lead sulphate, barite or barium sulphate, celes- tite or strontium sulphate, chalcanthite or cop- per sulphate, gypsum or calcium sulphate, and Icieserile or magnesium sulphate. Volcanic gases generally contain sulphur in the forms of sulphur dioxide and sulphureted hydrogen, and com- ]Knmds containing sulphur are found in certain organic materials, such as the volatile oils of mustard and garlic, hair, wool, bile, and albuminous substances. It is generally be- lieved that native sulphur has been formed by the action of sulphur dioxide on hydro- gen disulphide. Sulphur may also be ob- tained by decomposing certain mineral sul- phides, such as pyrite. The commercial ar- ticle is usually obtained by purifying native sulphur bj- fusion, or by distillation, and is jjroduced largely in Sicily, where it occurs mixed with celestite, gypsum, limestone, and marl. The ore, after being carefully hand-picked, was for- merly heated in heaps from which the liquid sul- phur collected in a trough at the bottom, whence it was ladled out; but as this process was very wasteful, kilns came into use, in which the sul- pliur ore was piled and ignited at the bottom ; the heat jicnetrated slowly into the mass, and as the sulphur gradually melted it ran to the bot- tom of the kiln, where it was collected and then cast into molds. Sulphur may also be extracted from ores by using a solvent such as carbon di- sulphide, from which it is then separated by dis- tillation. Crude commercial sulphur usually contains about 3 per cent, of earthy impurities, which may be removed by distillation, in which case the sulphur is first melted and then heated to the boiling-point, the vapor of sulphur then passing into a large chamber, where it condenses and falls to the floor in the form of a light yel- low crystalline powder commonlv known as flowers of sulphur. This is cast into slightly conical wooden molds, when it is known as roll sulphur or brimstone, and sometimes it is al- lowed to cool in the chamber, when it is obtained in large crj'stalline masses called block- sulphtir. Sulphur (symbol, S; atomic weight. 32.07) occurs in several allotropic modifications. One of these is a brittle solid that crystallizes in the rhombic system, but that on heating passes into transparent yellowish-brown needles of the mono- clinic system. Both of these forms are soluble in carbon disulphide. The modifications of sul- phur that are insoluble in carbon disulphide in- clude plastic, amorphous, yellow, and black sul- phur. There is a variety of sulphur that is soluble in water. This is known as colloidal sul- phur and is obtained by passing hydrogen disul- phide into an aqueous solution of sulpliur di- oxide. Sulphur has a specific gravitv of about 2.03, and melts variously from 111° to 11.5° C. It is a poor conductor of heat and electricity. The element itself is extensively used in the arts and manufactures, as in making gunpowder and matches, and in medicine. Sulphur combines with oxygen to form a di- oxide (SO.) and a trioxide (SO,), which in turn combine with water to form sulphurous and sul- phuric acids (H2SO3 and H.SOi respectively).