Page:Popular Science Monthly Volume 16.djvu/686

 the ingenuity of the nineteenth century in so extensive and indefatigable 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 manufactories 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 Tessié 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 Gaslight Company. Its advantages, however, are subjected to an obvious drawback, 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 introduction of the recent American process, which has proved both in theory and practice a consummation and a contrast to the whole previous 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 availability of water-gas as fuel. In fact, the rapid progress and generally anticipated 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 illuminating and non-illuminating or fuel-gas.

Disregarding details, the apparatus consists, substantially, of a