272 CHEMICAL ELEMENTS. 



of chemical action is so great that they become incan- 

 descent, many of them glowing with extreme brilliancy. 

 If hydrogen gas is mixed with this element (chlorine) 

 they unite, under the influence of light, with explosive 

 violence, giving rise to a compound, muriatic acid, which 

 combines with water in an almost equally energetic 

 manner. Nitrogen, as it exists in the atmosphere, 

 mixed with oxygen, appears nearly inert ; with hydrogen 

 it forms the pungent compound, ammonia ; with carbon, 

 the poisonous one, cyanogen, the base of prussic acid ; 

 with chlorine it gives rise to a fluid, oily in its appearance, 

 but which, when merely touched by an unctuous body, 

 explodes more violently than any other known com- 

 pound, shivering whatever vessel it may be contained in, 

 to atoms ; with iodine it is only slightly less violent ; 

 and in certain combinations with silver, mercury, gold, 

 or platinum, it produces fulminating compounds of the 

 most dangerous character.* Here we have elements 

 harmless when uncombined, exhibiting the most de- 

 structive effects if their combinations are at all disturbed ; 

 and in the other case we have inert masses produced 

 from active and injurious agents. 



We regard a certain number of substances as ele- 

 mentary -, that is to say, not being able, in the present 

 state of our knowledge, to reduce them to any more 

 simple condition, they are considered as the elements 

 which by combination produce the variety of sub- 

 stances found in the three kingdoms of nature. 



We have already spoken of the atomic constitution of 

 bodies. It remains now to explain the simplicity and 

 beauty which mark every variety of combination under 

 chemical force. As a prominent and striking example, 

 water is a compound of two gaseous bodies, oxygen and 

 hydrogen : 



If we decompose water by means of galvanic elec- 



* Graham's E'ements of Chem-'stry. New Edition. 



