76 GASEOUS BODIES. 



with atmospheric air or oxygen, it is highly inflammable. 

 A mixture of two parts by measure of hydrogen with one 

 part of oxygen will explode most violently if ignited, and 

 a small jet of it in a state of ignition produces a most 

 powerful heat,* causing steel and platinum to melt in- 

 stantly like wax. A jet of this gas, ignited on lime, 

 produces that intense light called Drummond's Signal 

 Light, and is that by which objects seen in the bxy-hy- 

 drogen microscope are illuminated. 



Hydrogen gas is frequently found combined with car- 

 bon in mines and coal-pits, and is by the miners called 

 fire-damp. It sometimes generates very suddenly, when, 

 on the introduction of a light, an explosion takes place, 

 producing the most fatal effects. Sir Humphry Davy, in 

 order to prevent the dreadful results above alluded to, 

 invented some years since a lamp called a safety -lamp, 

 which miners may use without risk. The safety-lamp 

 is a lamp surrounded with fine wire gauze, and is so 

 formed through the fact that flame will not pass through 

 small apertures in metallic substances. A stream of 

 hydrogen gas from a small orifice made to fall upon a 

 piece of spongy platinum will render the platinum red 

 hot, and ignite the gas. 



Hydrogen gas is easily obtained for experiment by 

 pouring a mixture of one part of sulphuric acid with four 

 or Jive parts of water, over iron filings, or, what is much 

 better, over granulated zinc in a retort ; by the action 

 of the acid the water becomes decomposed, the oxygen 

 unites with the metal and forms an oxide, while the hy- 

 drogen escapes. This gas, in combination with carbon, 

 similar to the Jire-damp above named, may be obtained 

 in great abundance in the summer time from ditches or 

 other stagnant water, by inverting a vessel filled with 

 water, and stirring up the bottom of the ditch with a 

 stick, when large bubbles will rise, which may be caught 

 in the vessel. 



Hydrogen is abundantly distributed in nature, form- 



* A jet of oxygen gas, made to pass through the flame of a spirit 

 lamp, will produce nearly the same effect ; alcohol being almost pure 

 hydrogen. 





