WATER AS FUEL. 655 



After all that has been said of it, the nineteenth century furnishes 

 an ever-fresh and amazing retrospect. Within the memory of the 

 living these now common facts — too vast and sublime, however, to be 

 called familiar — were hid, with the great bulk of modern science, in- 

 deed, from the sages of the world. Oxygen had but just been discov- 

 ered, a hundred years ago ; hydrogen was unknown ; water was sup- 

 posed to be an elementary substance ; fire and flame were mysteries ; 

 what the sun might be, and the nature of its light and heat, nobody 

 could guess. After hydrogen had been found elsewhere, it was dis- 

 covered (in 1781) that water is the result of its combustion with oxy- 

 gen, and in 1805 that two parts in three of the vast volume of that 

 element pervading and covering the earth are contributed by this ethe- 

 real ingredient. Several ways to dissociate the two gases were found, 

 but the common and practical method was and is the contact of steam 

 with red-hot carbon. This, in the absence of free oxygen, results in a 

 transfer of the water oxygen to the carbon fuel in combustion, leaving 

 the water hydrogen free. Red-hot iron answers a similar purpose, 

 forming an oxide of iron (rust) in place of carbonic acid ; but the con- 

 sumption of so valuable an article as iron in the process has hitherto 

 excluded this method from practical use, although there is now some 

 prospect that by deoxidizing the iron-rust it may become available 

 over and over for the elimination of hydrogen at a minimum of cost. 



Until a recent date it has been quite generally taken for granted 

 that, since to separate the two gases of water must cost as much heat 

 as they will evolve by reuniting in combustion, there could be no pos- 

 sible profit in forcing the separation for the sake of fuel. Hence, the 

 application of water hydrogen to practical purposes has been regarded 

 as visionary. But there are some considerations on the other side also 

 that seem to have been overlooked. The unavoidable waste in burn- 

 ing solid fuel has been found to range from fifty per cent, as a mini- 

 mum in the arts up to ninety-five per cent, as a common proportion in 

 stoves, and thus to exceed by several volumes the whole cost of ob- 

 taining from water a gaseous fuel which can be used with but insig- 

 nificant waste. Besides this, the doubted possibility of economizing 

 the carbonic acid has also been realized, and that hitherto worthless 

 incumbrance has been incidentally recarbonized in the process and 

 utilized as carbonic oxide, to an economic success. Direct economies 

 in the process have also been achieved, preventing great waste of heat 

 in various ways, including that of a large amount hitherto lost in cool- 

 ing off the finished gas. These recent — and American — improvements 

 have suddenly given a practical character to the manufacture of wa- 

 ter-gas, and a practical purpose to the elucidation of the subject. 



Notwithstanding an unbroken succession of failures in the economic 

 sense for more than half a century, the unlimited and ubiquitous stores 

 of hydrogen " ore " have mightily stimulated inventors to the task of 

 extracting treasure from these mines of fuel. Few objects have en- 



