GUMS, ETC. 89 



alcohol, as well as in cold and boiling water. They 

 are easily soluble in an aqueous or alcoholic solu- 

 tion of potassic hydrate, assuming a yellow or red- 

 dish color. They are also dissolved, but with more 

 difficulty, in hot concentrated acetic acid, ammonia, 

 and the alkaline carbonates. 



Unripe oranges may be used in testing for this 

 substance. 1 



GUMS. 



At present we have no 'certain micro-chemical 

 reaction for gums. The different sorts are in- 

 soluble in alcohol. They swell strongly in water 

 and are not colored blue by iodine, either alone or 

 followed by sulphuric acid. Cell-walls which con- 

 tain gum assume a red color when treated with 

 Hanstein's aniline violet. 



VEGETABLE MUCUS 2 



Is a comprehensive name used to designate a num- 

 ber of different substances which are closely 

 related to the gums, but are still imperfectly 

 known in many respects. They are distinguished 

 from gums by the yellow or blue color which they 



1 Pfeffer: Hesperidin. Bot. Zeitung, 1874, p. 481. Mika: Beitrage 

 zur Morphol. u. mikroskop. Nachweisung des Hesperidins. Magyar 

 novenytany lapok, I., p. 93. Known to me only through Just's Jahres- 

 bericht. 



2 Kirchner and Tollens : Untersuchungen liber den Pflanzenschleim. 

 Ann. d. Chem. and Pharm., Bd. CLXXV., p. 205. 



