10 



seed {semenis). Besides the above, certain drugs consist of the 

 juices of plants and are without definite structure {opium, aloes) 



Chemistry of Plants 

 The chief elements found in plants are Carbon, Hydrogen, 

 Oxygen and Nitrogen. These elements usually 'occur in combina- 

 tions as fats, carbohydrates, tannins, resins, alkaloids, glucosides, 

 acids, terpenes, etc., together with inorganic salts. 



Chapter IV. 

 PLANT CONSTITUENTS 



Alkaloids. Many of the most important and active plant 

 constituents are alkaloids. They exist in almost all parts of a plant 

 but are in largest proportions in the seeds and roots. They repre- 

 sent, in the greater number of cases, the active principle of the 

 plant from which obtained and many of them are classed with the 

 most powerful poisons. 



They may be defined as natural nitrogenous organic bases form- 

 ing salts with acids, i. e., they are organic substances coyiimi- 

 ing nitrogen, of basic character, uniting with acids without the 

 elimination of hydrogen, forming well defined and usiudly crystal- 

 line salts. The alkaloidal salts of the halogens are called hydro- 

 bromides, hydrochlorides, etc., and not the bromides, chlorides, etc. 

 They contain nitrogen, carbon, hydrogen and most 'of them oxygen. 

 Those containing oxygen are solids and comparatively nonvolatile, 

 (cocaine) while those which do not contain oxygen are liquid and 

 ' volatile (nicotine). 



All alkaloids have certain common characteristics. Bitter 

 taste, alkaline reaction to litmus, strong physiological action, and 

 leave no post-mortem changes. The alkaloids differ from their 

 salts in solubility. The former being freely soluble in chloroform, 

 ether, and oils, less so in alcohol and almost insoluble in water, 

 while the latter behave almost exactly opposite, being soluble in 

 water and alcohol and almost insoluble in chloroform, ether and oils. 



Experiments: — Solubility of alkaloids and their salts. 



1. Test solubility of quinine and quinine sulphate (alkaloidal 

 salt) in water, alcohol, ether and chloroform, 



