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.
630/792 page 614
![ozonised oxygen comes in contact witli the olefiant gas a detona- tion occurs usually accompanied with the formation of white fumes.1 Acetylene or Ethine, C2H2. Density = 12-97. 382 This gas was discovered and its composition determined in 1836, by Edmund Davy,2 who prepared it by treating with water the black mass obtained in the manufacture of potassium. The existence of this gas was afterwards observed by some other chemists, but it was not until the year 1859 that Berthelot3 investigated it completely. Acetylene is always produced by the incomplete combustion of many volatile organic substances, especially of ethylene, coal-gas, and other hydrocarbons, as well as the vapours of alcohol, ether, &c. Acetylene is also formed when the vapours of these organic liquids are passed through red-hot tubes. Acetylene is remarkable as being the only hydrocarbon which has been obtained by the direct union of its elements. These only combine together at the highest temperature which can be artificially produced. In order to prepare acetylene in this way the electric arc, obtained by the passage of a powerful current between two poles of gas carbon, is employed. These carbon poles are fitted through apertures in a globular glass vessel, through which a slow current of pure hydrogen is allowed to pass. Acetylene can also be prepared in any wished-for quantity from ethylene dibromide. If this substance be heated with an alcoholic solution of caustic potash, the following reactions take place:— (1) C2TT4Br2 4- KOH = C2H3Br 4- KBr + II20. (2) 02H3Br + KOH = C2H2 4 KBr 4 II20. To remove any vapodrs of the very volatile bromethene which may be carried over from this operation, the gases evolved from the boiling liquid are allowed to pass through a second flask containing a boiling alcoholic solution of caustic potash. Properties.—Acetylene is a colourless difficulty condensable gas, having a specific gravity of 0'92, with a very unpleasant penetrat- ing smell, which is always observed when the flame of a Bunsen 1 Houzeau and Renanl, Comptes Rcndiis, lxxvi. 572. 2 Reports of British Association, 1836, p. 62. 3 Ann Chim. Rhys. [3], lvii. 82.](https://iiif.wellcomecollection.org/image/b28122409_0001_0632.jp2/full/800%2C/0/default.jpg)
