60 GAS ILLUMINATION. 



twice as much carbon as the last. It is heavier 

 than it, and is also called the Heavy hydro-car- 

 bonate. It burns with a bright white flame, like 

 that of the best wax candles. It has been called 

 the olejiant gas, because, when mixed with chlo- 

 rine in an exhausted vessel, or over water, a pe- 

 culiar fluid was formed, resembling a thick oil, but 

 which has been termed by Dr. Thomson, Chloric 

 ether. 



Bi-carbureted hydrogen may be procured by 

 heating, in a retort, four parts of sulphuric and 

 of one alkohol ; when the mixture boils the gas 

 comes over. 



Gas Illumination. — The carbureted hydrogen 

 gases are now extensively employed for the pur- 

 pose of giving light. When coal is put into an 

 iron retort placed in a furnace, an inflammable gas 

 is given out, which is a mixture of the two above- 

 mentioned species of hydro-carbonate, together 

 with small quantities of carbonic acid gas, car- 

 bonic oxide, sulphureted hydrogen, tar, ammonia, 

 and water. These last substances are separated 

 by passing the gas through a mixture of quicklime 

 and water; and the purified gas then passes into 

 the gasometer^ from which it is distributed by 

 means of pipes. The coal that has been thus acted 

 upon, being deprived of its volatile principle, is con- 

 verted into colce. 



The kind of coal, fittest for the production of 

 good gas, is that which contains most bitumen and 

 least sulphur. 



Messrs. J. and P. Taylor have lately taken out a 

 patent for the production of carbureted hydrogen 

 gas from oil. The oil is decomposed by suffering 

 it to drop into a bent iron tube, laid through a 

 furnace. The oil is separated into charcoal and 



