656 THE POPULAR SCIENCE MONTHLY. 



gaged the ingenuity of the nineteenth century in so extensive and in- 

 defatigable researches, with (prior to 1874) so little result. Scores of 

 patents have been taken out, mostly by French and English inventors, 

 for different methods of obtaining and employing water hydrogen for 

 illuminating purposes ; and a number of minor towns and manufac- 

 tories in Europe have been and are to this day supplied, by as many 

 different methods, with water-gas. Want of space forbids us to review 

 these methods as to their successes or defects. The common inherent 

 obstacle to their progress is the lack of a sufficient margin of economy 

 to overcome the immense vested interests that oppose any departure 

 from the use of bituminous coal. Such a margin can never be attained 

 under the waste inseparable from the use of retorts, heated externally, 

 to which all the European inventors have adhered. One of the best of 

 their efforts is that of Tessie du Motay, adopted and modified by the 

 Municipal Gaslight Company of New York, and lately purchased of 

 the latter for the down-town district held by the old New York Gas- 

 light Company. Its advantages, however, are subjected to an obvious 

 di'awback, in addition to others before mentioned, in a necessity for 

 reheating the gas to give it a fixed character. 



In short, the test of successful propagation had never been met by 

 any system, in any measure, on either side the Atlantic, until the in- 

 troduction of the recent American process, which has proved both in 

 theory and practice a consummation and a contrast to the whole pre- 

 vious history of invention in its line. 



But illuminating gas, and the struggles of half a century to cheapen 

 it by water hydrogen, have interested us but incidentally as leading 

 up to a later and still more important result — the practical availabil- 

 ity of water-gas as fuel. In fact, the rapid progress and generally an- 

 ticipated success of the electric light have given pause to all present 

 enterprise in illuminating gas. New movements are almost suspended, 

 and shares in the oldest and most profitable works are no longer the 

 favorite investment. A probability has suddenly appeared that the 

 uncounted millions of irrecoverable capital invested in gas mains, 

 pipes, holders, etc., may eventually find no other employment but to 

 supply fuel-gas to the households that have hitherto depended on them 

 for light. In view of such a prospect the feeling of the gas interest 

 toward water hydrogen must become seriously modified. The lately 

 dreaded process begins to look like a friend in need — the only hope of 

 rescuing much capital from total loss in the not improbable event of a 

 satisfactory and economical diffusion of the too concentrated electric 

 light. 



Our remaining space, then, will be dedicated mainly to fuel-gas, 

 and the process as modified for that product ; first, briefly describing 

 the apparatus, and the distinctive processes for producing by it illumi- 

 nating and non-illuminating or fuel-gas. 



Disregarding details, the apparatus consists, substantially, of a 



