Arsenic Sublimation

If finely powdered realgar is heated with aqueous sodium sulphide in a sealed tube at 100° C., a thioarsenate is formed and arsenic, which may be contaminated with sulphur, is precipitated.12 Heated with arsenious oxide, metallic arsenic sublimes and sulphur dioxide is evolved.13... 

Chemical Properties.—Arsenic trisulphide may be reduced to arsenic by heating in a stream of hydrogen the arsenic sublimes. The reaction begins at about 300° C.,10 but proceeds more readily if the sulphide is first fused with an alkali carbonate.11 A similar reduction occurs when the sulphide is heated with a mixture of charcoal and alkali carbonate12 or lime when heated with potassium cyanide,13 an oxalate14 or with a metal such as silver or iron the latter if in excess yields arsenide. 

Arsenic sublimes on heating and is unchanged in dry air, but a film of oxide is formed in moist air heated in air at 180°C, arsenic forms arsenic trioxide of tine odor of garlic, poisonous insoluble in HC1 but soluble in concentrated HNOj or concentrated H2SO4 to form arsenic acid soluble in hot NaOH solution healed with chlorine forms arsenic trichloride heated with metals forms metallic arsenides. When arsenic is heated in a tube and tile vapor cooled (1) slowly (that is, in the hot part of the tube) black arsenic is formed, and this form is converted into the gray at 360°C, (2) rapidly (that is. in the cold part of the tube) yellow arsenic is formed, and this form is quickly converted into the gray by the action of light. Yellow arsenic is soluble in CS2,... 

The physical properties given in Table 75 are for the metallic forms. Arsenic sublimes at the ordinary pressure the m.p. as given is that for 36 atmospheres. 

The Countess of Essex, still consumed by hate for Thomas Overbury, plotted to kill him. She procured the help of an apothecary named Eranklin. Eranklin supplied poisons, including rosalger (a compound of arsenic), sublimate of mercury and white arsenic, to Weston, the under-keeper of the Tower. Weston, under heavy bribery from the Countess, mixed small quantities of poison into Overbury s food over the course of 4 months. Overbury became very unwell and eventually died. At first his death was thought to be the result of syphilis, but after some time, suspicion was aroused and the case was brought to trial. 

See also ARSENIC SUBLIMATE, ARSENIC SULPiiURUM, RED ORPIHENT,... 

SAL AMMONIAC Vf- WAX TUTIA OIL OF TARTAR WHITE VITRIOL ARSENIC SUBLIMATE SALT... 

Arsenic is a shiny, gray solid that is brittle. Under certain conditions, it can become a dull, yellow solid. Arsenic sublimates when heated. 

Also of interest were such corrosive substances as acids, hydroxides, and ammonium chloride, which on heating turns into ammonia and hydrochloric acid and readily attack metals. Because arsenic sublimes like mercury, forms soft alloys like mercury, and has a sulfide that looks like the sulfide of mercury, alchemists regarded arsenic as a kind of mercury, and much use was made of arsenic s property of coloring metals. Vitriols (copper and iron sulfates) were also of interest to the alchemist, probably because of their colors. Copper sulfate forms beautiful blue crystals and solutions, and iron sulfate is green. We can confidently write about the preceding materials and techniques because of the efforts of a few early alchemical practitioners to preserve their knowledge in writing. Three are considered here pseudo-Democritus, Mary the Jew, and Zosimos. 

He writes in symbols red precipitate of mercury heated in a retort gave much vitriolic air, no fixed air, very little sublimate (yellowish-red), and metallic mercury. Scheele mentions his memoir on arsenic, saying that he showed how this acid can be sublimed into ordinary arsenic simply by continued heat and although I clearly perceived the reason for this, even at that time, still I was unwilling to mention it there in order to avoid prolixity . He found thdt when arsenic acid is very strongly heated it melted, boiled , and white arsenic sublimed. 

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