HYDROGEN FOR ILLUMINATION. 169 



are other inventions for the same purpose, and doubtless some 

 will be made of great practical value ; but it would be much 

 more desirable that gas, capable of yielding the fullest in- 

 tensity of light, should be made at the gas-works. The con- 

 sumer should be saved the trouble of making his own light. 

 Whether there be any advantage in heating gas previous 

 to its combustion in the naphthalizing process or not, we 

 offer a suggestion by way of improvement. The vessel to 

 be heated over the jet might be concave underneath, provided 

 with a tube passing off from the highest point of the concavity 

 into the open air, or chimney, so that it would carry off the 

 products of combustion. The heated vessel might be a double 

 cylinder or a cylindrically wound spiral tube. 



Hydrogen for Illumination. — Various processes have been 

 devised or adopted for obtaining light by means of hydrogen : 

 and this gas is obtained for the purpose by one of three 

 methods, in each of which cases water is decomposed, by 

 incandescent iron or coal, or magnetic force. 1. Vertical iron 

 pipes are filled with scrap-iron, and heated externally to a 

 high temperature ; steam is introduced, forming oxide of iron 

 and liberating hydrogen, which passes into a gas-holder. In 

 order to reduce the oxide of iron to the metallic state, to be 

 again subjected to the action of steam, carbonic oxide gas is 

 passed through the heated pipes, and becomes carbonic acid, 

 which escapes. The carbonic oxide is obtained by passing 

 the waste gases of the fire through a fire or ignited carbon. 

 Instead of carbonic oxide, carburetted hydrogens may be em- 

 ployed, such as tar, &c. 



2. Another method for obtaining hydrogen, mixed with 

 carbonic oxide and other gases, is to pass steam through or- 

 dinary gas-retorts charged with carbonaceous matters, brought 

 to a state of high ignition, whereby these gases are generated 

 together with carbonic acid. A purifier serves to remove the 

 carbonic acid from the combustible gases. 



3. By means of a magnetic battery, hydrogen and oxygen 

 are separately liberated from decomposed water. 



In order to utilize the hydrogen, &c., obtained bv any of 

 P 



