APPENDIX. 827 



stitution of one or of two atoms of for the corresponding H 2 or H 4 . 

 An example or two may be cited : 



C 2 H 4 , ethene ; C 2 H 4 OH, ethene glycol ; C 2 H 4 3 , glycolic acid ; 

 C 2 H 2 4 , oxalic acid; and C 3 H 6 , propene ; C 3 H 6 OH 2 , propene glycol; 

 C 5 H 8 3 , lactic acid ; C 3 H 4 O 4 , malonic acid, 



The next series of hydrocarbons, C n H an _ a , is represented by C 2 H 2 , 

 acetylene; the next C n H 2n _ 4 , by terebinthene, C 10 H if .; the next C n H 2n ._ r , 

 by benzene, C 6 H 6 . 



From these we obtain triatomic alcohols, e.y. 9 glycerine, C 3 H 8 OH S , 

 tetratomic alcohols, e.g., erythrite, C 4 H 6 OH 4 , and hexatomic alcohols, 

 e.g., mannite, C c H 8 OH 6 ; from the last, the carbohydrates are derived. 



Of the hydrocarbons, only one is, as we have said, found in the body, 

 viz., methane; of the alcohols, cholesterine, C 26 H 43 OH, a monatomic, 

 and glycerine, C 3 H 3 OH 3 , a triatomic alcohol. 



Of the aldehydes and ketones (analogous products to aldehyde, ob- 

 tained from isomeric alcohols), acetone, or propyl ketone, is found in blood 

 and in urine, particularly in diabetes. The glucoses are aldehydes of 

 mannite, and the other carbohydrates are derived from that class. 



Fatty Acids. Formic, acetic, propionic, butyric, caproic and caprylic, 

 are all more or less represented in the secretions and tissues of the body. 

 Palmitic and stearic in fats. 



Glycol Acids. Lactic acid, of which there are three isomeric bodies, 

 and leucic acid and two other acids, oxalic and succinic. 



Aromatic Series. The foundation is the benzol ring, C 6 H G , and all 

 bodies containing this radicle are closely related. They differ in regard 

 to the position in the ring of the H atoms which are replaced, as well as 

 in regard to the substances which replace them; the derivatives often 

 occur in the decomposition of proteids. Phenol or oxybenzol (C 6 H 5 0) 

 is found in combination in the urine and faeces. Oxybenzoic acid 

 (C C H 4 , OH, COOH) is a common decomposition product of proteids ; one 

 atom of H is replaced by hydroxyl and another by carboxyl. The action 

 of Millon's reagent is due to the benzol ring. 



Nitrogenous Products of Proteid Decomposition. 



Amines. These are bodies of the ammonia type (NH 3 ) in which one 

 or more of the H atoms of the ammonia are replaced by hydrocarbon 

 radicles; e.g., NH 2 , CH 3 = methylamine or mono-rnethylamine. Tri- 

 methylamine, N(CH 3 ) 3 , often occurs in putrefaction. 



Protamines. These are basic proteid bodies which give the Biuret 

 reaction ; on decomposition they yield the nitrogenous bases but no leucin 

 or tyrosin. They occur in the decomposition of all proteids and also as 



