SECT. i. HYDROGEN. 1 1 



the thunderstorm what is that in comparison with the 

 electric energies which silently and continually exert 

 themselves in every chemical change ? Why, the electric 

 force in a single drop of water, and disturbed when that 

 water is decomposed, is of itself greater than in the 

 electricity of a whole thunderstorm. Those of us who 

 limit our appreciation of the powers of oxygen to the 

 energies displayed by this element in its feebly active 

 state, form but a very inadequate idea of the aggregate 

 results accomplished by" it in the economy of the world.' 

 Oxygen is the only known gas that is allotropic, and is 

 the only known substance that is doubly allotropic, that 

 is existing in three different states similar to oxygen, 

 ozone, and antozone. 



Hydrogen when pure is an invisible gas without smell 

 or taste ; it is a constituent of various acids and alka- 

 lies, but is itself neither acid nor alkaline. It is highly 

 inflammable, burning with a pale light, and, as already 

 mentioned, a combined jet of oxygen and hydrogen pro- 

 duces heat of 8801!, which is so intense that nothing can 

 withstand it. It is the lightest substance known. A 

 balloon having the form of a globe ten feet in diameter, 

 would hold 32^ pounds weight of common air, while two 

 pounds weight of hydrogen gas would fill it. Associated 

 with this small quantity of ponderable matter, hydrogen 

 has an enormous power of combination, but its activity 

 is only called forth by some exterior and exciting cause. 

 A mixture of two measures of hydrogen and one of 

 oxygen gas would remain inert for ever, but the instant 

 an electric spark is sent through it, a bright flash and 

 an explosion takes place, and the result is water : thus 

 a tremendous force lies quiescent in that bland element. 



Hydrogen gas is introduced into the atmosphere by 

 imperfect combustion, but it is instantly diffused and 

 becomes harmless, for aeriform fluids are capable of 

 rapid and perfect diffusion through ojie another, each 



