CONCLUSIONS 



169 



each class of organic compounds therefore resembles some 

 inorganic compound, which serves as a type. Thus : — 



Hydrogen, HH, 

 Water, HOH . 



Potassium chloride, KCI 

 Ferric hydroxide, Fe(0H)3 

 Hydrochloric acid, HCl 

 Hydro-sulphuric acid, HgS 

 Sodium chloride, NaCl 

 Ferric chloride, FeCls 

 Ammonia, NH3 



"In mineral chemistry the radicles are simple, in organic 

 chemistry they are compound; therein consists the whole 

 difference. The laws whereby the compounds are formed, and 

 their reactions regulated, are the same in both." (Dumas.) 



To understand the relation between the members of each 

 group of organic compounds, it must be pointed out that, just 

 as in an inorganic compound an atom of hydrogen can be re- 

 placed by, or substituted for, an atom of another monad 

 element {e.g. H in HCl by Na in NaCl), so, in an organic 

 compound, an atom of hydrogen can be replaced by a monad 

 organic radicle. Thus, an atom of hydrogen in methane, CH^, 

 can be replaced by methyl, CH3, forming ethane, CH3 - CH3 

 or C2Hg. One atom of hydrogen in ethane, CH3 — CH3, can 

 be replaced by methyl to form propane, CH3 - CHg - CH3 

 or CsHg. So, also, an atom of hydrogen in ethyl alcohol 



