SUBSTITUTIONS. 343 



Mention some > SUBSTITUTION COMPOUNDS. It Was 



instances of stated, in a previous paragraph, that there 



the substitu- ., , ,, . . - 



tionofradi- are many cases of substitution of the ele- 

 cals ' ments for each other, without material 



change of properties. Certain cases of substitution of 

 organic radicals for the elements remain to be men- 

 tioned. Theoretically considered, they form, perhaps, 

 the most important discoveries which have for years 

 been made in organic chemistry. Ammonia, as the 

 student is already informed, is a volatile base whose 

 molecules consists of one atom of nitrogen and three 

 atoms of hydrogen. For one of these atoms of hydro- 

 gen, a molecule of the radical ethyle may be substituted, 

 without very materially affecting its properties. The 

 new ammonia thus formed is, like the first, a volatile 

 base resembling the first so nearly in odor that it must 

 have been repeatedly mistaken for it when accidentally 

 produced. It is, however, a liquid at ordinary temper- 

 atures. This body has received the name of etliyla- 

 mine. Methylamine is another body of the same series, 

 produced by the replacement of two of the atoms of am- 

 monia by the radical ethyl. Triethylamine is a third. 

 By a similar substitution of hydrogen in ammonia by 

 the radical methyl, another series is produced. Other 

 radicals yield other series. 



868. OTHER SUBSTITUTIONS. There are 



Mention other 



cases of sub- other bodies which result from the substi- 

 stitution. tution of different radicals or the metal pla- 

 tinum, for the different atoms of hydrogen. Substitu- 

 tions may even exist in the substituting radicals. All 

 of these bodies retain the type of ammonia, and all of 



