532 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



■ Primary alcohols may be prepared 1 by reduction of the aldehyde with nascent 



hydrogen, 



<H ; niO + H. 2 = ril rn OH 



Ethyl aldehyde. Ethyl alcohol. 



and similarly by reduction of the acid. 



Secondary Alcohols. -Prom propyl alcohol upward there are alcohols isomeric with the 

 primary alcohols, but in which the grouping 11 — CIIOII — 11 is characteristic. These are 

 secondary alcohols, and may be produced by the action of nascent hydrogen on ketones: 



CH s -CO (II :! + H 2 = CH 3 -CHOH-('ll 



Acetone. Isopropyl alcohol. 



Tertiary Alcohols. — These have the general formula R 3 ^-rOH. 

 Monobasic Acids — The Fatty Acids (formula, C n H 2n 2 ). — 



Formic acid. II COOH. Capric acid, C 9 H 19 COOH. 



A., tic acid. CH 3 COOH. Laurie acid, C n H 23 COOH. 



Propionic acid, C 2 H 5 COOH. Myristic acid. C 13 H. 27 COOH. 



Butyric acid, C 3 H 7 COOH. Palmitic acid, C 15 H 31 COOH. 



Valerianic acid, C + H 9 COOH. Stearic acid, C 17 H 33 CO( ) 1 1 . 



( laproic acid, C 5 H„COOH. Arachidic acid, C 19 H 39 COOH. 



(Enanthylic acid, C 6 H 18 COOH. Cerotic acid, C 26 H 53 CO< )1 1 . 



( !aprylic acid, C 7 H 15 COOH. Melissic acid, C 29 H 59 COOH. 



These are organic compounds of acid reaction in which one atom of hydrogen is replace- 

 able by a metal or an organic radical. Combined with glycerin the higher members of the 

 series (from (', up) form the neutral fats of the organism. By distillation of a fatty acid 

 with alkaline hydrate, a hydrocarbon is obtained containing one carbon atom less than 

 the acid used. 



CH 3 COONa + NaOH = CH 4 + Na,C0 3 . 



I'n ixiration. — in) Through oxidation of alcohols or of aldehydes, 



C,,H 5 OH + 2 = CH3COOH + H 2 0. 

 (b) Through the action of carbon dioxide on the sodium compound of alcohol radicals, 

 CH 3 Na + C0 2 = CH 3 COONa. 



Compounds op Methyl. 



Methane, or Marsh-gas, CH 4 . — This gas is produced by intestinal putre- 

 faction, and is the only hydrocarbon found in the body. It is formed iu largest 

 quantities from the fermentation of cellulose, which takes place, according to 



Hoppe-Seyler, thus : 



C 6 H 10 O 5 + H 2 = C 6 H 12 6 . 



C 6 H l2 6 = 3CH 4 + 3C0 2 . 



Tappeiner 2 finds that less ('1I 4 than C0 2 is produced in cellulose fermenta- 

 tion in the intestine, and that the lower fatty acids (acetic to valerianic) are 

 also formed. This putrefaction is especially great in the caecum of herbivora. 

 Methane is also a product of putrefaction of proteid (but not of casein, since 

 it is not present when milk is fed). Through the put refaction of cholin, a 



1 Again attention is calleil to the fact that the list of these reactions is in no wise complete, 

 but only intended to be suggestive of what .should he mastered from a text-book on general 

 chemistry. 



5 Zeiischrijl fur Biologic, 1884, Bd. 20, S. 84. 



