473 THE POPULAR SCIENCE MONTHLY 



GAS MANUFACTURE AND GAS COMPANIES. 



By WILLIAM E. SIMMONS. 



THERE are three kinds of gas, named after the substances from 

 which they are obtained, as coal, petroleum (or naphtha), and 

 water gas. The first two are produced by destructive distillation of 

 coal and petroleum, or naphtha, the last by passing a curi'ent of 

 steam over a bed of incandescent anthracite. Coal-gas is the kind in 

 general use, petroleum or naphtha gas being used chiefly as an 

 enrichef ; and water-gas, used in only a few places and for a compar- 

 atively short time, is as yet on its trial. The general principles 

 involved in the manufacture of each kind of gas will first be noticed; 

 then the relative merits of the products will be considered in regard 

 to quality, cost of manufacture, and respective peculiarities ; and, 

 finally, a comparative view will be taken of several leading com- 

 panies; after which the relationship of gas companies to municipali- - 

 ties, and the subject of competition, will be examined. 



When coal is subjected to high heat in a closed vessel, certain 

 gases and vapors are evolved, some of which are combustible, and 

 some, like steam, condensible, a residue of charcoal or coke being left 

 behind. This process is termed destructive distillation, and the 

 property displayed by coal is common to all vegetable and animal 

 substances; but only coal and petroleum have been used economically 

 in the production of illuminating gas on an extensive scale. The 

 distillation is the most important operation in the manufacture, but it 

 is necessary to remove from the gas, before it is fit for burning, the 

 condensible vapors, as tar, water, etc. ; and those non-condensible 

 gases, as carbonic anhydride (carbonic acid), which either largely 

 diminish the. illuminating power, or which give rise, in the burning of 

 the gas, to injurious products of combustion, such as sulphuretted 

 hydrogen and ammonia. The removing of these very materially 

 affects the cost of production. The distillation is effected in iron or clay 



1 Abstract of a Report to the City of Boston, a. d. 18*76, by the Gas Commissioners, 

 Messrs. Charles F. Choate, John Felt Osgood, and Edward S. Wood, appointed in 

 January, 1875, who were instructed " to investigate and report 1. On the quality and- 

 price of the gas furnished in Boston, as compared with that of other large cities in this 

 country and Europe; 2. Whether any improvements can be made in the present 

 methods of manufacturing gas by the different companies in this city; 3. Whether it 

 would be expedient for the city to undertake the manufacture and supplying of gas for 

 public and private lighting; and, 4. Whether any further legislation is desirable to enable 

 gas-consumers, or the municipal authorities, to secure a prompt and impartial investiga- 

 tion of complaints against private companies, and an efficient remedy for any abuses of 

 which they may be found guilty." 



