SIMPLE HYDROCARBONS. 32X 



II. Oxygexated Hydrocarboxs : mostly resins. 



III. ASPHALTUM AXD MlXERAL COALS. 



I. SIMPLE HYDROCARBONS. 

 Marsh-Gas. — Light Carburetted Hydrogen 



Colorless and inodorous gas in the pure state. Inflam- 

 mable, and burns with a yellow flame. Composition Cil 4 = 

 Carbon 75, hydrogen 25 = 100. 



Obs. This gas (mixed with more or less carbon dioxide 

 and nitrogen) often rises in bubbles through the waters of 

 marshes, whence its name ; and frequently it is discharged 

 from fissures into coal mines in large quantities, constituting 

 the fire-damp of the mine. Such natural discharges, called 

 blowers, sometimes continue for months. It is the cause of 

 the explosions in mines, a mixture of it with the atmo- 

 sphere exploding on the approach of the flame of a can- 

 dle. It destro} T s life both by the concussion occasioned, by 

 the exhaustion of the atmosphere of oxygen, and by the 

 production of carbon dioxide which takes place. The gas 

 which issues from the oil springs or wells of Western New 

 York (Fredonia), and Eastern Pennsylvania, is marsh-gas 

 mixed with other vapors of the Marsh-gas series. It is used 

 in some places for lighting houses, and even villages ; and 

 also for other purposes where heat is required. 



The gas bubbling up from a marsh in Europe afforded 

 Websky Carbon dioxide 2-1)7, marsh-gas 43-36, nitrogen 

 53*67=100. The first of these ingredients is in fact one 

 of the more abundant results of decomposition, whether 

 vegetable or animal ; and the percentage is here small 

 because the gas is soluble in water, and because it readily 

 enters into combinations with the earthy ingredients of 

 plants. 



Petroleum. 



Mineral oils, varying in density from 0*60 to 0*85. Solu- 

 ble in benzine or camphene. They consist chiefly of liquids 

 of the Naphtha and Ethylene series. The composition of 

 the Naphtha or Marsh-gas series is expressed by the general 

 formula, C n H 2ll + 2, of which Marsh-gas is the first or 

 lowest term ; and that of the Ethylene series by the for- 

 mula, C n H 2ll = Carbon 85*71, hydrogen 14-29 = 100. The 

 oils vary greatly in density from the lightest naphtha, too 



