Selenite

“ And after dissolving calcareous Earth, forms with it a Selenite. In its concentrated State it dissolves Silver, Tin, &c. when diluted, Copper, and Iron.
Distilled from Salt, it is not unctuous; is little heavier than common Water; less corrosive than from Vitriol; and after dissolving calcareous Earth, forms with it, not Selenite, but a fixed Sal Armoniac. In its concentrated State it dissolves Lead, &c.
Distilled from the Swedish Stone, it is heavier than Acid of Salt, less heavy than the Vitriolic. It dissolves the Calxes of Metals more readily than Metals themselves. ”

“ Selenite gypsum crystal from Bastrop County, Texas.
Selenite is found in cracks and cavities in rocks. Good crystals have been collected at Gyp Hill, a salt dome southeast of Falfurrias in Brooks County, and some selenite has been mined there. Selenite crystals also occur scattered through clays, particularly along creek banks, in Lee, Fayette, Bastrop, and several other counties.
Another variety of gypsum is known as fibrous gypsum. It is made up of slender, brittle, needle-like fibers that fill the cracks in some rocks. If fibrous gypsum has a silky or pearly luster, it is called satin spar. ”

“ But if the seleniate of soda be mixed with muriate of ammonia and heated, selenium, nitrogen and water come over, no trace of sulphur appearing. The selenium may, however, be dissolved in excess of nitric acid, and the selenious acid produced tested by [p472] muriate of baryta, which would then separate sulphuric acid if present; the clear solution is to be saturated with carbonate of soda, evaporated to dryness, and the mixture of selenite and nitrate of soda obtained, fuzed in a porcelain crucible over a spirit-lamp. ”

“ The Gypsum is nothing more than a Selenite, less elegant than the Rhomboidal or plated Kinds. Those resemble the foliaceous Talcs; and these the softer of the Alabasters. We may always by Glasses distinguish the flaky Texture of the Selenite in the Gypsum; and those unerring Tests by Weight and Firmness, give convincing Proofs of the Truth. Gypsum is lighter as well as softer than Spar; but differs very little in either of these Qualities from the pure Selenite: To which we may add the Effect of Fire ”

“ A powerful oxidising agent is required in order to convert selenious and tellurous anhydrides into selenic and telluric anhydrides, and, moreover, it must be employed in excess. If chlorine be passed through a solution of potassium selenide, K2Se, telluride, K2Te, selenite, K2SeO3, or tellurite, K2TeO3, it acts as an oxidiser in the presence of the water, forming potassium selenate, K2SeO4, or tellurate, K2TeO4. The same salts are formed by fusing the lower oxides with nitre. ”

“ Some parts of the earth were still warm. The shale is of a brown colour and thin slaty structure, with an earthy fracture. It contains many interspersed crystals of selenite; between its lamina there is much powdery alum, mixed with sulphur, and it is traversed by veins of brown selenite, in slender prismatic crystals. ”

“ For were we to meet with the purest Veins of that Metal, by removing only one Turf, not a Selenite would think it worth his while.
"This is a Place of Peace and Tranquillity, and this World is exactly adapted to the Temper of its Inhabitants: Nature here is in an Eternal Calm; we enjoy an everlasting Spring; the Soil yields nothing noxious, and we can never want the Necessaries of Life, since every Herb affords a salubrious Repast to the Selenites. ”

“ It acts upon the metals in the same manner, and even dissolves gold. The seleniates are also very similar in properties to the sulphates, and both classes of salts are isomorphous. The seleniates give the same characteristic odour before the blowpipe as the selenites. Their solutions give white precipitates with the salts of barium, strontian and lead, insoluble in nitric acid. If a soluble seleniate is boiled with hydrochloric acid, selenic acid is set free, and is reduced to selenious acid, sulphurous acid will then precipitate reduced selenium from the solution. ”

“ Selēnol′ogy, selenography.—adj. Selēnōtrop′ic, turning to the moon.—ns. Selēnot′ropism, Selēnot′ropy. [Gr. selēnē.]
Selenite, sel′en-īt, n. a transparent and beautiful variety of gypsum: a salt of selenium: a supposed inhabitant of the moon.—adjs. Selenit′ic; Selenitif′erous. [Gr. selēnitēs (lithos, stone) , moon-like—selēnē, the moon.]
Selenites, sel-ē-nī′tez, n.pl. a genus of coleopterous insects.
Selenium, sē-lē′ni-um, n. an element discovered by Berzelius in the refuse of a sulphuric-acid factory in 1817.—n. Sel′ēnate, a compound of selenic acid with a base.—adjs. ”

“ When crystalline, it has a pearly lustre, is transparent, and goes under the name of Selenite. Common Gypsum resembles the other earthy limestones, but it is softer, and may be readily distinguished by its not effervescing with acids.
To the minerals now enumerated may be added the following, which are of frequent occurrence, but not in great quantities; namely, carbonate of magnesia, oxide of iron, iron pyrites, rock-salt, coal, bitumen, schorl and garnet.
These simple minerals, either in separate masses or mingled more or less intimately together, compose almost wholly the earth’s crust. ”

“ But I have no Despair; and tho' it never should succeed with me, it may with others: When that is seen, the other, more important as it is, need not be supposed impossible.
Nothing is more familiar than the Production of what it is the Custom to call, Selenitical Salts; Urine affords them; and some Preparations of Sulphur; but to recrystalize Selenite is, to produce, from a clear Fluid, pellucid dodecahacedral Rhombs, flexile, not elastic, and not soluble again in Water: And he who shall effect this, need not despair of recrystalizing also Spar. ”

“ Rock Salt.—Intense yellow sodium flame; fusibility about 1; microcosmic salt with copper oxide shows strong chlorine reaction—a fine blue flame surrounding the bead when re-introduced into the flame. It is soluble in water.
Selenite (Gypsum) .—Fusibility about 2.5; brilliant flame; in closed tube it becomes white and opaque and much water is given off; with soda, on charcoal, sulphur reactions are obtained; soluble in hydrochloric acid. ”

“ If a plate of crystal, such as selenite, be placed between the two Nicols, and turned round in its own plane, it will be found that in certain positions at right angles to one another no effect is produced. ”

“ The water of almost every spring is of such nature that it will not dissolve, but curdles, soap; and cannot be used for dressing several kinds of food. Water of this description is denominated hard, a property owing to the great proportion of earthy salts which it holds in solution, and which, at the same time, are not in such abundance as to impair its taste. The most common of these salts is selenite, or sulphat of lime (192) , and chalk, or carbonat of lime (140) ”

“ The Greeks called the stone Selenitis Lithos, because they said it waxed and waned with the moon, a belief quaintly expressed by Trevisa in 1398 as follows: “Selenites is a stone of Perse, grene as grasse. It shineth with a white specke and foloweth the moon and waxyth and waneth as the moon doeth.” Some old stories tell of a belief that little Moon men which Howell, a 17th century writer, calls “Selenites or Lunary Men,” flung these stones deep in the earth. The Selenite was regarded as a love attractor and a stone to restore harmony between quarrelsome lovers. ”

“ Though there have been so many volcanoes, and selenite, gypsum, lime, and aluminous schist frequently occur, neither sulphur nor rock salt have been discovered, and but very little alum. Mineral springs are numerous, but not much frequented. ”

“ GYPSUM, a common mineral consisting of hydrous calcium sulphate, named from the Gr. γύψος, a word used by Theophrastus to denote not only the raw mineral but also the product of its calcination, which was employed in ancient times, as it still is, as a plaster. When crystallized, gypsum is often called selenite, the σεληνίτης of Dioscorides, so named from σελήνη, “the moon,” probably in allusion to the soft moon-like reflection of light from some of its faces, or, according to a legend, because it is found at night when the moon is on the increase. ”

“ Almost immediately we must have come upon the Selenites. There were six of them, and they were marching in single file over a rocky place, making the most remarkable piping and whining sounds. They all seemed to become aware of us at once, all instantly became silent and motionless, like animals, with their faces turned towards us. ”

“ The making of these various sorts of operative must be a very curious and interesting process. I am very much in the dark about it, but quite recently I came upon a number of young Selenites confined in jars from which only the fore-limbs protruded, who were being compressed to become machine-minders of a special sort. The extended ‘hand’ in this highly developed system of technical education is stimulated by irritants and nourished by injection, while the rest of the body is starved. ”

“ Rock Salt (pseudomorphs) , Aust; Steatite, Tortworth; Talc, Tortworth; Vivianite, near Clifton.
Pyle Hill, near Clifton, is a well-known locality for Celestine. At Garden Cliff, near Westbury-on-Severn, the “bone bed” is well exposed, and in this bed occurs plenty of iron pyrites; and in the shales, as might be expected, crystals of selenite occur.
Leicestershire.—Gold occurs in the quartz veins round Pedlar Tor, Charnwood Forest. Garnets occur in “gneiss” at Brazil Wood (Mr. W. J. Harrison) . Copper pyrites, Molybdenum, Mount Sorrel and Breedon. ”

“ The absence of air entails the absence of water. It became, therefore, manifest that the Selenites, to support life under such conditions, must possess a special organization of their own, must differ remarkably from the inhabitants of the earth. ”

“ It decomposes when strongly heated. The selenates are isomorphous with the chromates and sulphates. A compound of selenium and sulphur has been described as resulting from the action of sulphuretted hydrogen on selenious acid, but A. Gutbier (Zeit. anorg. Chem., 1905, 43, p. 384) is of the opinion that in this reaction, at ordinary temperature, a simple reduction takes place, leading to the formation of a mixture of sulphur and selenium. Selenium sulphoxide, SeSO3, is formed as a yellowish crystalline mass when selenium is warmed with sulphur trioxide. ”

“ We have observed that melted selenium behaves to the other substances as water to a greasy surface, and we are inclined to think that, when selenium is used in connection with metals not chemically acted upon by it, the points of contact between selenium and the metal offer a considerable amount of resistance to the passage of a galvanic current. By using brass we have been enabled to construct a large number of selenium-cells of different forms. The mode of applying the selenium is as follows: The cell is heated, and, when hot enough, a stick of selenium is rubbed over the surface. ”

“ I think this experiment proves that selenic acid is not injurious to plants when used in small quantity, and that the acid is taken up and retained by plants, or at least by certain varieties of plants. The experiment, however, did not prove whether or not there was a partial replacement of sulphur trioxide by selenium trioxide or of sulphur by selenium. Having lately become possessed of large quantities of selenium compounds, I propose to grow plants in soil or water free from sulphur in any form, but supplied with potassium and ammonia selenates. ”

“ Selenium combines directly with hydrogen when heated in the gas, and with fluorine in the cold. It burns with a blue flame when heated in the air or in oxygen, at the same time giving a characteristic smell of rotten horseradish, a reaction which serves for the recognition of the element. It combines directly with nitrogen, phosphorus, antimony and carbon, and with all the metals (except gold) to form selenides, of which those of the alkali and alkaline earth metals are soluble in water. Metallic selenium is a conductor of electricity, and its conductivity is increased by light ”

“ The smallest trace of selenium may be detected by igniting a small piece of charcoal in the flame of oxidation, when the peculiar and unmistakable odor of decayed horse-radish will indicate the presence of that element. An orange vapor is eliminated if the selenium be present in any quantity, while there is an incrustation around the assay of a grey color, with a metallic lustre. ”

“ Solution.—The solution is effected by boiling with nitric acid or aqua regia, or by fusing with nitre. To separate the selenium, the solution is evaporated with an excess of hydrochloric acid and a little sodium or potassium chloride. This destroys any nitric acid that may be present, and reduces selenic acid (H2SeO4) to selenious (H2SeO3) . The solution is diluted with water, and treated with a solution of sulphite of soda. It is warmed, and at last boiled. The selenium separates as a red precipitate, which (on boiling) becomes denser and black. ”

“ Chem., 1857, 71, p. 279) fuses the commercial selenium with potassium cyanide in a stream of hydrogen, takes up the melt in water and passes air through the solution; the precipitated tellurium is filtered off, and the solution then supersaturated with hydrochloric acid, when selenium is gradually deposited. E. Divers, (Chem. News, 1885, 51, p. 199) dissolves the element in boiling concentrated sulphuric acid and reduces the resulting selenious acid with sulphur dioxide, filters off the precipitate and washes it with water and alcohol. ”