AMINES AND AMIDES. 817 



Santonin solutions give a white precipitate with silver, zinc, 

 and mercurous salts; with an alcoholic solution of potassium 

 hydrate they yield a scarlet red liquid, which gradually becomes 

 colorless. Santonin taken internally confers upon the urine a 

 dark color resembling the color of urine containing bile; upon 

 heating such urine it turns cherry-red or crimson, the color dis- 

 appearing on the addition of an acid, arid reappearing on 

 neutralization. 



QUESTIONS. 



451. To which group of substances is the term "carbohydrates" ap- 

 plied? 



452. State the general properties of carbohydrates. 



453. Mention the three groups of carbohydrates, and the composition 

 and characteristics of the members of each group. 



454. Mention some fruits in which grape-sugar, and some plants in 

 which cane-sugar is found. 



455. What is the difference between grape-sugar and cane-sugar, and 

 by what tests can they be distinguished ? 



456. From what source, and by what process is milk-sugar obtained ? 



457. What is starch, what are its properties, by what tests can it be 

 recognized, and what substance is formed when diastase or diluted acids 

 act upon it ? 



458. Where is cellulose found in nature, and what are its properties? 



459. What three compounds may be obtained by the action of nitric 

 acid upon cellulose, and what are they used for? 



460. Which substances are termed glucosides? Mention some of the 

 more important glucosides. 



47. AMINES AND AMIDES. ORGANIC BASES. 

 ALKALOIDS. 



Forms of nitrogen in organic compounds. Nitrogen may be 

 present in organic compounds in three forms, viz., ammonia, 

 cyanogen, nitric acid, or derivatives of these compounds. Sub- 

 stances containing nitrogen in the nitric acid form may either 

 be organic salts of this acid (nitrates), or may have been formed 

 by replacement of hydrogen atoms by the nitric acid radical 

 N0 2 . These latter compounds, termed nitro-compounds, such 

 as nitro-cellulose, nitro-benzene, nitro-glycerine, etc., do not 

 occur in nature, but are obtained exclusively by artificial means, 



