306 CHEMISTRY. 



Ammonium, (NH 4 )', and cyanogen, (CN)', you have learn- 

 ed, are called radicals, because they act like simple elements 

 in certain cases. Now water is H O H; if you remove 

 one H, you have left O H, or (OH)', which acts also like 

 a radical, taking an important part in the building up of or- 

 ganic bodies. This radical, called hydroxyl, is monatomic, 

 or has one bond of affinity, as indicated above, and hence 

 may take the place of one atom of hydrogen in any com- 

 pound. Suppose, then, we substitute one atom of hydroxyl, 

 (HO)', for one atom of H in the hydrocarbon we have been 

 studying, CHHHH, what kind of a body will result? 



This question can of course be answered by experience 

 only, and experience has taught the chemist that a body 

 very closely resembling common alcohol is formed. Act- 

 ually the substance is methylic alcohol, or CH 3 (OH). This 

 leads us to the next subdivision of the scientific classifica- 

 tion, which is that of alcohols. 



422. Alcohols. You are now prepared to understand the 

 relation between alcohols and hydrocarbons; for common 

 alcohol has become the type of a vast number of bodies, 

 some of which resemble it in its physical properties, but 

 many of which are crystalline solids, and have no apparent 

 connection with it. This relation is not founded on resem- 

 blance in properties, but on similarity of constitution, which, 

 indeed, is the key to this scheme of classification. 



Alcohols, then, are substances derived from hydrocar- 

 bons by the substitution of one or more groups of hy- 

 droxyl, (OH)', for hydrogen. Take the case of common 

 alcohol : the formula of this body determined by analysis 

 is C 2 H 6 O ; certain facts show its relations to ethane, which 

 is C 2 H 6 . Now follow carefully the following formulae, 

 and you will see how common alcohol is a derivative of 

 ethane : 



CCHHHHHH = ethane ; remove one H and substitute 



