Arsenic amalgam

Sodium, potassium, mercury and silver do not alloy with tantalum even at high temperatures 5 attempts to prepare alloys with arsenic, antimony, lead, zinc and tellurium have also failed, but the formation of an alloy with silver, copper and tin for making a dental amalgam with mercury has recently been claimed.6... 

Arsenic in the form of an amalgam is used to a small extent in medicine. It also finds application as a poison in fly-traps.3... 

Mercury Arsenides.—Arsenic does not dissolve in mercury even at the boiling point,2 nor has an amalgam been obtained by the action of sodium amalgam on moist arsenious oxide 3 or by electrolysis of a solution of arsenic trichloride using a mercury cathode 4 in the latter case arsenic is deposited on the surface of the mercury but does not dissolve. Nevertheless, two arsenides of mercury, which appear to be definite compounds, have been prepared. 

The reduction of arsenic compounds to arsine by nascent hydrogen may also be effected in alkaline medium thus in the presence of caustic alkali with zinc,10 aluminium11 or sodium amalgam,12 and also in ammonia or ammonium chloride with zinc.13... 

The pan-amalgamation process has found more favour than the patio process. The ore in the form of fine sludge is stirred in iron pans with a mixture of mercury, common salt, and cupric sulphate. When the action is complete, the excess of mercury is drained off, and the amalgam is allowed to settle, and then decomposed by heat. In the Boss system the process is continuous, a series of pans and settlers being employed. Some silver ores, notably those containing sulphides of arsenic, antimony, copper, iron, and zinc, are roasted with common salt before amalgamation. 

Anthraquinone-2-arslmc acid is prepared in a similar manner to the 1-arsinie acid, a yield of 23 per cent, resulting. hYom boiling acetic acid it crystallises in needles, which remain unchanged at 270° C. It has similar solubility and reactions to the 1-compound, bxit yields very little anthraquinone when treated witli sodium amalgam, showing that the arsenic residue is more flrmly bound in this case. 

Mercury di-o-tolyl may be j repared by the sodium amalgam method (see mercury diphenyl, Method 5). In this case 8 per cent, amalgam is used, and the yield is about 33 per cent. Tlie compound forms quadratic crystals from benzene, M.])t. 108° C. B.pt. 219 C. at 14 mm. The reactions of mercury di-o-tolyl with tlie trichlorides oi boron, phosphorus, and arsenic, also with nitrogen tri- and tetr-oxides, are similar to those described under mercury diphenyl (p. 74). 

Mercury di-m-xylyl is prepared by the addition of 150 grams of l 3 4-bromoxylene to 2 per cent, sodium amalgam and the mixture then heated for twelve hours at 140° to 150° C. The compound er stallises in fine needles, M.pt. 169° to 170° C., difficultly soluble in alcohol or cold ether, readily soluble in hot benzene. It is decomposed by hot hydrochloric acid into the hydrocarbon and mercuric chloride. Heated witli phosphorous trichloride at 230° C. it yields m-xylylmereuric chloride and m-xyiyldichlorophosphine, whilst arsenic trichloride gives m-xylyl-dichloro-arsine.. ... 

Azobenzene has been manufactured by reduction of a suspension of nitrobenzene by Na(Hg). Further reduction to hydrazobenzene is possible if higher temperatures and concentrations of alkali are employed [79]. The corresponding arsenic compounds may be prepared from a phenylarsenoxide by amalgam reduction thus -aminophenylarsen-oxide yields 80% H9NC6H4As=AsC6H4NHt on treatment with 4% Na(Hg) in methanol [80]. 

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