CHEMISTRY OF PLANTS 3 



of basic character, uniting witli acids without the elimination of 

 hydrogen, forming well defined and usually crystalline salts. The 

 alkaloidal salts of the halogens are called the hydrobromides, hydro- 

 chlorides, etc., not the bromides, chlorides, etc. They contain nitro- 

 gen, carbon, hydrogen, and most of them oxygen. Those containing 

 oxygen are solids and comparatively non volatile (cocaine), while 

 those which do not contain oxygen are liquids and volatile (nicotine). 



Characteristics. All alkaloids have certain characteristics: 

 Bitter taste, alkaline reaction to litmus, strong physiological reaction 

 and cause no post mortem changes. The pure alkaloids dijffer from 

 their salts in solubility. The alkaloids are freely soluble in chloro- 

 form, ether, and oils, less soluble in alcohol and almost insoluble in 

 water, while the salts behave almost exactly opposite, being soluble 

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

 oils. 



Nomenclature. The United States Pharmacopoeia makes all the 

 names of alkaloids end in ine (Latin, ina) as quinine (quinina), 

 morphine (morphina), to distinguish them from the neutral prin- 

 ciples ending in in (Latin, inum) as digitalin (digitalinum), santonin 

 (santoninum). This is a very simple way in which to distinguish 

 these principles, and it is to be regretted that this distinctive spelling is 

 not followed in. all text-books. 



Incompatibles. Alkaloids are incompatible with many sub- 

 stances and it is necessary to know the chief substances with which 

 they are incompatible in order to prescribe them intelligently. The 

 most common incompatibles are : 



1. Alkalies which combine with the acid radicle and throw down 

 the less soluble pure alkaloids as a precipitate, while some alkaloids 

 are destroyed by strong alkalies. 



2. Tannic Acid which forms comparatively insoluble tannates. 



3. Iodine, Iodides and Bromides which form comparatively in- 

 soluble iodides, bromides or double salts. 



4. Mercuric Chloride which forms insoluble double salts. 



In all the above cases, the alkaloids are simply rendered less 

 soluble in water, and if a large volume of water or fair percentage 

 of alcohol is present, the precipitation will not occur. 



Besides the alkaloids there are several other active principles of 

 plants which should be mentioned. Those with neither acid nor 

 basic characters are called "neutral principles." K they are not 

 very poisonous and have a very bitter taste, they are termed " bitter 

 principles." They differ from glucosides in not being converted into 

 glucose and from alkaloids in not being precipitated by tannin or 

 mercuric potassium iodide. , . i j. i j. 



Glucosides are those principles or substances derived from plants 

 which when treated with dilute acids or submitted to the action of 

 ferments split into glucose as one of the decomposition products. 



