32 ANIMAL CHEMISTRY LECTURE II. 



Butyric Group 



C 4 H IO Butene C 4 H 8 Butylene 



C 4 H I0 Butyl-alcohol 



C 4 H 10 O a Butyl-glycol 



C 4 H 8 Butyr-aldehyd 



C 4 H 8 O z Butyric acid C 4 Hg 0, Crotonic acid 



C 4 H 8 '0 3 Bulatic acid 



C 4 He 4 Succinic acid C 4 H 4 4 Fumaric acid 



C 4 H 6 5 Malic acid C 4 H 4 5 Metatartric acid 



C 4 H 6 6 Tartaric acid 



(31.) Of the correlated bodies comprised in groups of this 

 description, chemists attach far greater importance to those occu- 

 pying certain particular positions, than to the remainder. Thus, 

 the principal terms of every well represented organic group such 

 as the propionic, and butyric, to which I have just directed your 

 attention are, I st, the monatomic alcohol ; 2nd, the monobasic 

 acid corresponding thereto ; 3rd, the diatomic alcohol or glycol ; 

 and 4th, the dibasic acid corresponding thereto, as shown below in 

 the case of the 2-carbon and 3 -carbon groups, for instance : 



Principal Group-Terms 



(C a H 6 Alcohol (C 3 H 8 Propyl-alcohol 



( C a H 4 0, Acetic acid \ C 3 H 6 O z Propionic acid 



C a H 6 0, Glycol (C 3 H 8 3 Propyl-glycol 



C.,H 3 4 Oxalic acid (C 3 H 4 4 Malonic acid 



The monobasic acid, you observe, differs in composition from 

 its correlated alcohol by containing one additional atom of oxygen 

 in place of two subtracted atoms of hydrogen ; while the dibasic 

 acid differs from its correlated glycol by containing two additional 

 atoms of oxygen in place of four subtracted atoms of hydrogen. 

 But even of these four principal members of every complete 

 organic group, by far the most importance is attached to the 

 monobasic acid, which is accordingly selected in preference to the 

 alcohol, glycol, or dibasic acid as the characteristic term or pivot 

 of the group. As a rule, the series of monobasic acids is more 



