340 ORGANIC CHEMISTRY. 



type, is the group which remains permanent, while the 

 individual atoms which compose it are changed. 



860. COMPOUND RADICALS. Many or- 



Ilhistrate the ' 



subject of com- game bodies, although compounds, com- 

 P cah d Tadl ' P ort themselves as if they were elementary 

 substances. Some of these are, as it were, 

 metals ; forming oxides, chlorides, and salts, like the 

 true metals, which have already been considered. 

 Others correspond more nearly to the metalloids. Each 

 being organic, and like a metalloid, the root of a whole 

 series of compounds, is called an organic radical. The 

 term radical is sometimes applied, for similar reasons, to 

 chlorine, bromine, and other elementary substances. 

 As the organic substances above referred to, are com- 

 posed of different elements, they are called compound 

 radicals. 



861. ILLUSTRATION. A molecule of or- 

 ple of acom- dinary ether is composed of four atoms of 

 poundradical carborij fi ve o f hydrogen, and one of oxy- 

 gen. But the carbon and hydrogen atoms are grouped 

 together, forming a compound radical called ethyle, 

 with which the oxygen is then com- 

 bined to form ether or oxide of ethyle. 



Alcohol, as illustrated in the figure, is 

 the hydrated oxide of this radical. Al- 

 dehyde, a substance to be hereafter more particularly 

 described, has the same composition as alcohol, with 

 the exception that two atoms of hydrogen have been 

 removed from the radical. Acetic acid is formed from 

 aldehyde by the re-placement of the removed hydrogen 

 by the same number of atoms of oxygen. Ethyle itself 

 may be prepared indirectly from the oxide, as potassium 



