Volume 1
A treatise on chemistry / by H.E. Roscoe and C. Schorlemmer.
- Henry Enfield Roscoe
- Date:
- 1877-1892
Licence: Public Domain Mark
Credit: A treatise on chemistry / by H.E. Roscoe and C. Schorlemmer. Source: Wellcome Collection.
538/792 page 522
![The same compoimd is easily obtained by passing dry chlorine over heated arsenic which burns to chloride of arsenic. In order to purify it from excess of chlorine it must be recti- fied over some more arsenic. Properties.—Arsenic trichloride is a colourless oily liquid and has a specific gravity at 0° of 2-205. It does not solidify at - 29° and boils at 134° (Pierre), evolving a colourless vapour which has a specific gravity of 6'3 (Dumas). It is an extremely powerful poison, and evaporates in the air with the emission of dense white fumes. When arseniuretted hydrogen is led into the liquid, arsenic separates out (Janowsky); thus:— AsCl3 + AsH3 = As2 + 3HC1. When brought in contact with a small quantity of water, star-shaped crystalline needles of arsenic oxychloride, As(OII)2C1 separate out (Wallace). In contact with a large quantity of water, it decomposes into arsenic trioxide and hydrochloric acid, and when the solution is distilled, arsenic trichloride comes over together with the vapour of water; this explains the fact that the hydrochloric acid prepared from arsenical sulphuric acid invariably contains arsenic. Arsenic trichloride absorbs dry ammonia, forming a solid compound having the composition AsC13+3NII3 which dissolves in alcohol, being deposited from alcoholic solution in white crystals.1 ARSENIC AND BROMINE. Arsenic Tribromide. AsBr3. Vapour Density = 157*8. 329 In order to prepare this compound, powdered arsenic is added to a solution of one part of bromine in two parts of carbon disulphide until the solution becomes colourless. Then bromine and arsenic are added alternately until the colour of the first disappears ; the liquid is poured off clear, and the disulphide of carbon allowed to evaporate spontaneously. Arsenic tribromide forms colourless deliquescent crystals which possess a strong arsenical odour (Nickles), and melt at about 20°. It has a specific gravity of 3-66, and boils at 220°. By the action of water, it is decomposed in a similar way to the chloride. I 1 Wallace, Phil. Mar/. [4] xvi. 358.](https://iiif.wellcomecollection.org/image/b28122409_0001_0540.jp2/full/800%2C/0/default.jpg)
