Sulphur allotropy

Many elements including sulphur, carbon and oxygen can exist in two or more forms with different physical, and often chemical, properties such elements are said to exhibit allotropy and the different forms are known as allotropes or allotropic forms. 

Tuinstra, F., Structural A ects of the Allotropy of Sulphur and other Divalent Elements, U. Waltman, Delft, 1967. 

Sulphur, selenium and tellurium exhibit allotropy, and in certain of their crystalline forms the elements are isomorphous. As would be expected from the increased positive character of tellurium, the allotropy of this element is less well defined. In the liquid condition the elements arc miscible with one another and yield mixed crystals the ternary system, S— Sc—Tc, exhibits neither the formation of compounds nor ternary eutectics, but contains two zones of complete miscibility in which there exist mixed crystals of selenium and tellurium with sulphur, and of sulphur and tellurium with selenium.2... 

Allotropy in the Liquid State.—When the temperature of sulphur is gradually raised from the melting-point, a notable change is observable near 1 GO" C., the colour of the liquid beginning to deepen, whilst the fluidity commences to decrease.6 The occurrence of this change, or at... 

Allotropy in the Solid State.—When molten sulphur is allowed to solidify, the modifications present give rise to corresponding solid forms, the liquid A-sulphur producing crystalline sulphur (rhombic, monoclinic or nacreous, according to the conditions), whilst the deep... 

The analogy of selenium with sulphur is observable in the occurrence of allotropy, although no rigid relationship can be traced between the various forms of the two elements. 

Occurrence, Extraction, Refining, Applications—The Allotropy of Sulphur Changes in tho Vaporous State, Allotropy in tho Liquid. State, Allotropy in the Solid Stato, Crystalline Forms of Sulphur, Amorphous Sulphur— Colloidal Sulphur—General Physical Properties of Sulphur—Chemical Propertius—Valency—Atomic Weight—Detection and Estimation. 

Between 98 and 122° -sulphur is stable. Its monoclinic crystals also contain 8-membered rings. The two modifications (with a range of stability and a definite transition temperature) are the best-known example of enantio-tropic allotropy ... 

Tire first ease of dynamic allotropy, namely, that of liquid sulphur, was investiaated bv Alexander Smith and his collaborators (Joum. Amr. 

A number of facts lead to the view that in the case of phosphorus as in the case of sulphur, a condition of dynamic allotropy exists (Cohen and Olie, Z. pkysikaL Chem., 1910, 71, I Stock and Stamm, Ber., 1913, 46, 3497 Smits and Bokhorst, Z, pkysikaL Chem, 1916, 91, 249). The equilibrium relations would therefore be those of a pseudo-binary system or of a system of perhaps even higher order. For a discussion of the phosphorus systems from this point of view, see Smits, FersL K, Akad. Wetensch, Amsterdam, 1912, 21, 753 1914, 22, 1145 Smits and Bokhorst, Z, physikal. Chem., 1916, 91, 249,... 

On the basis of his theory of allotropy, according to which there separates from a liquid mixture in dynamic equilibrium, not a pure solid substance but a solid phase consisting also of an equilibrium mixture (a solid solution), Smits has suggested a diagram for the equilibrium relations of sulphur. This diagram, however, has not yet... 

In 1833 Berzelius used the names empirical (empirische) and rational (rationelle) formulae for those giving the result of analysis (e.g. alcohol C H 0) and those showing the electrochemical division of the atoms (e.g. C H + H 0 or C H + 0), respectively. In 1840 he introduced the name allotropy for the existence of different varieties of an element (sulphur, carbon, silicon) different forms of a compound may contain different allotropic forms of an element, e.g. Sa and Sj3 in pyrites and marcasite. 

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