S
Sulfur

atomic no. 16, atomic wt. 32.066, metal, row 4, col. 7B, val. 2-4-6, orbits 2-8-6


{Merck Index - © 1952 by Merck & Co., Inc.}

Sulfur. S; at. wt. 32.066 ± 0.003; at. no. 16; valence 2-4-6. Has been known from very early times. Occurs both in the free state and in combination, mainly as sulfides and sulfates; constitutes 0.05% of the crust of the earth.

Prepn.: Gill, Frasch, et al., cited by Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry 10, 14 (1930).

Sulfur exists in several allotropic forms: two stable crystalline forms, octahedral, rhombic or Alpha-sulfur and monoclinic, prismatic or, Beta-sulfur; various metastable crystalline forms; at least two amorphous and two liquid; forms; a number of other modifications has been described. The exact relationship existing among the various modifications is not yet fully understood. See also sulfur, pharmaceutical.

Rhombic, octahedral or Alpha-sulfur: Amber colored crystals; the stable form at ordinary temperature. d. 2.06; when heated to 94.51° becomes opaque owing to the formation of monoclinic sulfur. When rapidly heated, in. 214.5°.

Monoclinic, prismatic or Beta-sulfur: Light-yellow, opaque, brittle, needle-like crystals; stable between 94.5°-120°. Passes slowly into the rhombic form on standing. d. 1.96; b. about 444.6°.

Sulfur is insoluble in water; sparingly soluble in alcohol, in ether; soluble in carbon disulfide (one gram / 2 ml.); soluble in benzene, in toluene.

Ignites in air above 261°, in oxygen below 260°, burning to the dioxide; combines readily with hydrogen; combines in the cold with fluorine, chlorine, and bromine; combines with carbon at high temperatures; reacts with silicon, phosphorus, arsenic, antimony, and bismuth at their melting points; combines with nearly all metals; with lithium, sodium, potassium, Copper, mercury, and silver in the cold on contact with the solid; with magnesium, zinc and cadmium very slightly in the cold, more readily on heating; with other metals at high temperatures. Does not react with iodine, nitrogen, tellurium, gold, Platinum, and iridium.

Use: In manuf. sulfuric acid, sulfites, insecticides, plastics, enamels, metal-glass cements; in vulcanizing rubber; in syntheses of dyes; in making gunpowder, matches; for bleaching straw, wool, silk, felt, linen.

Commercially available.

Note: See also Sulfur, pharmaceutical.

{Mineral Deficiencies in Plants}

Sulfur occurs in plants as a constituent of proteins (e.g. cystine) and of certain volatile compounds such as mustard oil. It seems to be connected with chlorophyll formation although it is not a constituent of this substance. Its functions in connection with proteins and chlorophyll doubtless account for the similarity of its deficiency effects to those due ...

 
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