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.
626/792 page 610
![A mode of formation of methane by the slow decomposition of vegetable matter, somewhat similar to that taking place in the coal measures, occurs in ponds or marshes, whence one of the names of the gas is derived. The gas-bubbles which rise when a stagnant pool containing decomposing leaves and vegetable matter is stirred, consist essentially of marsh gas, which is mixed with carbon dioxide and nitrogen. The gas collected by Bunsen in July 1848, from a pond in the botanical gardens of Marburg, contained, after the absorption of carbon dioxide by caustic potash, the following :— Methane 48‘5 Nitrogen 51 5 Methane also invariably occurs amongst the products of the dry distillation of organic bodies, and hence it is present in very considerable quantities in coal-gas. 379 Preparation—(1). In order to prepare marsh gas an intimate mixture of one part of acetate of soda with four parts of soda- lime (a mixture of caustic soda and lime) is heated. This is best accomplished in a tube of hard glass closed at one end, and fitted with a delivery-tube at the other, or, in place of this, an iron tube or a copper flask may be employed. In order to prepare the gas as pure as possible, the mixture must only be heated to the point at which the gas begins to be evolved, but even with all care it is impossible to avoid the presence of some free hydrogen and some ethylene. This latter impurity may, however, be removed by passing the gas through a U-tube containing pumice-stone soaked in strong sulphuric acid. In a sample of the gas thus prepared and purified, Kolbe 1 found 8 per cent, of hydrogen. The formation of methane from acetic acid is shown by the following equation :— C2H,02Na+ NaCHI = Na2C03 + CII4. (2) Chemically pure methane is obtained from zinc methyl, Zn(CH3)2, which is decomposed by water as follows :—2 Zn(CH3)2 + 2H20 = Zn (OH)2 + 2CH4. (3) Marsh gas can be obtained synthetically by passing a mixture of sulphuretted hydrogen and the vapour of carbon disulphide over red-hot copper :—3 2SH2 + CS2 + 8Cu = CH4 + 4Cu2S. 1 Ausfuhrl. Lehrb. Orrj. Chemie., i. 275. 2 Frankland, Phil. Trans. 1852 [2], 417.](https://iiif.wellcomecollection.org/image/b28122409_0001_0628.jp2/full/800%2C/0/default.jpg)
