654 THE POPULAR SCIENCE MONTHLY. 



from the all-devourer, oxygen, and enters into innumerable uses. As 

 the inflammable ingredient of wood, of bituminous coal, of petroleum 

 and other vegetable and animal oils, we have it sealed up by Provi- 

 dence, as it were, for a temporary and portable fuel, pending the full 

 development of man's proper authority over the elements — temporary, 

 for it has long been a source of anxiety to economists that the resources 

 of forests and coal-fields are so finite and their prospect of exhaustion 

 so definite. It is evident from the coal " measures " that man was 

 never intended to remain dependent on what he could pick up ready 

 made for his needs, in respect of fuel any more than of other things ; 

 albeit this provisional supply for his infancy was made ample and ac- 

 cessible above all others. Even the novel service of carbon (which we 

 shall observe more particularly further on) in smelting hydrogen " ore " 

 from the vast mines of lake and ocean — as it does also the oxides of 

 other metals from telluric mines — bids fair to be divided with some 

 more unlimited artificial agency in due time. To the present time 

 carbon, diffused and heated to intense brilliancy in burning hydrogen, 

 has been our only artificial illuminant on a practical scale. And yet 

 it now seems likely enough to be superseded in this ofiice also, at no 

 distant day, by fixed illuminators excited by the combustion of hydro- 

 gen or the force of electricity. 



The better hydrogen becomes known, therefore, the more interest- 

 ing and important to us it is found beyond all other elements, oxygen 

 scarce excepted. To all the vital and delightful uses of water, as we 

 have seen, it adds also those of light and heat. For, although scarcely 

 luminous in itself, hydrogen is a principal source of the heat which 

 makes other substances luminous, and is thus a chief condition of illu- 

 mination. Terrestrial flame is generally hydrogen gas in the act of 

 combustion, colored and made brilliant with white-hot carbon also oxi- 

 dizing. Carbon may therefore be called a diffused illuminant, and the 

 only one of any importance available at a living temperature, although 

 in the terrific conflagration of the sun all things, even the most stable, 

 are diffused in gaseous incandescence. The more stable substances 

 that maintain their solid form in the comparatively moderate terres- 

 trial heat of burning hydrogen until they become intensely bright are 

 called fixed illuminators. Progressive examples may be cited : in plati- 

 num, the most non-fusible of metals, which endures and emits in light 

 the intensity of hydrogen burning in air ; and in lime, a still more re- 

 fractory substance, which glows with dazzling power in the fierce com- 

 bustion of hydrogen with pure oxygen, commonly known under the 

 name of calcium light. 



If Mr. Lockyer should succeed in verifying his startling hypothesis 

 that hydrogen may be in fact the only thing in the material universe 

 — not the water-parent only, but the all-parent — our present celebra- 

 tion of this great element would prove neither inopportune nor inor- 

 dinate ! 



