14 BULLETIN 102, PART 4, UNITED STATES NATIONAL MUSEUM. 
Three types of gas made from coal are in general use — coal gas, 
carbureted water-gas, and mixed gas. Coal gas is distilled from 
bituminous coal by heating the latter in retorts. Carbureted water- 
gas is produced as a result of the action of steam upon coke or 
anthracite, the nonilluminating water-gas thus produced being 
then “ carbureted,” or enriched, by the addition of a gas of high 
thermal and illuminating power made from oil. Mixed gas is a 
mixture of coal-gas and carbureted water-gas and is supplied in 
many cities in the United States, the coke from the coal-gas pro- 
duction furnishing the basis of the water-gas manufacture . 1 
The gas companies are by nature and in fact public utilities. They 
manufacture a necessity which does not lend itself to competition. 
They are private enterprises under municipal control, which is 
largely directed, however, to price restrictions, and is not con- 
structive in the way of compelling advances in technical procedure. 
With some exceptions, the average municipal gas plant is a small 
and antiquated organization, both in practice and in vision, far 
behind present possibilities of manufacture and application . 2 In 
some cities in the United States, the gas companies are in the nature 
of large public-service corporations, which have made considerable 
advance in gas production, but nowhere is there full by-product 
recovery and the price of city gas is uniformly high. 
Although the municipal gas plant now meets rather inadequately 
only a small share of the fuel needs of the community which it serves, 
it represents an established activity which can be converted into an 
organization that will supply all the fuel, whether gaseous or solid, 
that the community consumes. The transformation may retain the 
gas mains and much of the other equipment of the present type of 
plant, but in the place of the present procedure with relative neglect 
of by-product recovery will be substituted a by-product system of 
coal distillation, producing artificial anthracite, gas, ammonia, 
benzol, and tar. This will mean in each city a centralized purchase 
and consumption of raw coal, and a centralized distribution of prod- 
ucts. The output will be limited at first at least, by the demand for 
solid fuel. A production of ample solid fuel will give an excess of gas 
over that now produced, which will call for an expansion in the use 
of gas, both in the home and in industry. Such expansion will 
come as a result of cheaper gas, incidental to the proposed plan of 
1 In many cities the gas plant is hampered by the imposition of a standard based on candle-power. This 
is a survival of the flat-flame use of gas, and now that the incandescent mantle makes heat in the flame and 
not artificial enrichment in the gas the true object to be sought, a calorifice standard should supersede alto- 
gether an illuminating one. 
2 In Great Britain the gas industry is far in advance of that in the United States; allusion has already 
been made to the important rdle it has been able to play in that country by supplying toluol for explosive 
manufacture. It should be emphasized that the gas industry in the United States has been impeded by 
restrictions imposed by economic conditions and by the type of public control affecting its affairs and in 
consequence is by no means wholly responsible for such delinquencies as exist. 
