OXIDS OF CARBON, CARBONATES, ETC. IOQ 



the product is called water-gas. Carbon monoxid is pro- 

 duced in furnaces from the coke, which is mixed with ore, 

 and in the smelting and refining of ores, carbon monoxid 

 is an important reducing agent ; in fact, it is the main 

 reducing agent of the blast-furnace. 



129. Marsh Gas (Methane, CHJ. When vegetable 

 matter decays under water, where the supply of air is 

 incomplete, methane, CH 4 , is one of the products formed. 

 It is given off in bubbles from the surface of stagnant 

 pools. It often collects in coal mines, and is there called 

 fire-damp. CH 4 can be prepared in the laboratory in a 

 number of ways, and is a colorless, combustible gas, 

 which with air forms an explosive mixture. 



130. Hydrocarbons. A compound, as methane, com- 

 posed of hydrogen and carbon, is called a hydrocarbon. 

 There are a large number of such compounds, forming 

 series in which the members differ from one another 

 in composition by a definite number of C and H atoms, 

 as methane, CH 4 , and ethane, C 2 H 6 . The next mem- 

 ber is propane, C 3 H 8 ; CH 2 being the common difference 

 between the members of this series. By oxidation, re- 

 duction, and substitution, in which a part of the H is re- 

 placed with equivalent radicals, a large number of de- 

 rivatives, as alcohols, aldehydes, ethers and organic 

 acids, are formed. 



131. Petroleum. Petroleum is an oily liquid obtained 

 in some parts of the world by boring wells into the rock 

 strata in which it is found as a natural product. It is 

 a mechanical mixture of various liquid and solid hydro- 



