CONSTITUTION&quot; OF CHEMICAL COMPOUNDS. XXV11 



compounds is exactly the same as that of the hydrocarbon 

 itself. 



Just as marsh gas may be considered as the mother- 

 substance of a whole group of carbon-compounds, so, by re 

 placing its hydrogen-atoms by various groups, we obtain 

 compounds, each of which may, in turn, be looked upon 

 as the mother-substance of a subordinate group. It has 

 already been shown that the water-residue, hydroxyl, OH, 

 plays an important part in the structure of the two classes 

 of compounds known as acids and bases. If, for a hydro 

 gen-atom of marsh gas, we substitute OH, we obtain a 



H 

 compound H.^.OH = CH 3 (OH). This possesses the pro- 



H 



perties of the bases in general, corresponding to the sim 

 pler base K.O.H. We have in this case only CH 3 , instead 

 of the element K. Here, too, the hydrogen-atom, which is 

 in combination with oxygen, imparts to the compound its 

 characteristic properties, whereas the other hydrogen- 

 atoms present exhibit only those other general properties 

 which are met with in connection with the hydrogen-atoms 

 of other groups of carbon-compounds. One or all of these 

 latter can be replaced by other elements or groups, and 

 the compound still retains the properties originally im 

 parted to it by the hydroxyl group. We can, for instance, 

 replace one of these atoms by CH 3 , thus obtaining a com- 

 HH 



pound, H-C-C-O.H = C 2 H 5 (OH). This in every way re- 



HH 



sembles the body from which it is derived. We can, 

 further, in this compound replace one or more hydrogen- 

 atoms by elements or groups, without disturbing the hy- 

 droxyl-group. Let us again employ the group GIF. We 

 find that two products are formed, dependent upon the 

 hydrogen-atoms replaced : 



HUH 



H|HH II 



1. H.r &quot; &quot; 



C 



C^OOO.H, and 2. II-C OO H, 



H HH ii H 



and, just as in the case of the hydrocarbon C 4 H 10 , the two 

 products differ from each other in properties as well as in 

 constitution. 



