46 SOURCE AND ASSIMILATION OF NITROGEN. 



specting the quantity of sugar contained in different varieties of 

 maple-trees, growing upon unmanured soils. We obtained crys- 

 tallized sugars from all, by simply evaporating their juices, with- 

 out the addition of any foreign substance ; and we unexpectedly 

 made the observation, that a great quantity of ammonia was emit- 

 ted from this juice when mixed with lime, in the process of refin- 

 ing, as practised with cane sugar. The vessels which hung upon 

 the trees in order to collect the juice were watched with the 

 greatest attention, on account of the suspicion that some evil-dis- 

 posed persons had introduced urine into them, but still a large 

 quantity of ammonia was again found in the form of neutral salts. 

 The juice had no color, and had no reaction on that of vegeta- 

 bles.. Similar observations were made upon the juice of the 

 birch tree ; the specimens subjected to experiment were taken 

 from a wood several miles distant from any house, and yet the 

 clarified juice, evaporated with lime, emitted a strong odor of 

 ammonia. 



In the manufactories of beet-root sugar, many thousand cubic 

 feet of juice are daily purified with lime, in order to free it from 

 vegetable albumen and gluten, and it is afterwards evaporated 

 for crystallization. Every person who has entered such a manu- 

 factory must have been astonished at the great quantity of am- 

 monia volatilized along with the steam. This ammonia must be 

 contained in the form of an ammoniacal salt, because the neutral 

 juice possesses the same characters as the solution of such a salt 

 in water; it acquires, namely, an acid reaction during evapora- 

 tion, in consequence of the neutral salt being converted by loss 

 of ammonia into an acid salt. The free acid thus formed is a 

 source of loss to the manufacturers of sugar from beet-root, by 

 changing a part of the sugar into uncrystallizable grape sugar 

 and syrup. 



The products of the distillation of flowers, herbs, and roots, 

 with water, and all extracts of plants made for medicinal pur- 

 poses, contain ammonia. The unripe, transparent, and gelatinous 

 pulp of the almond and peach, emit much ammonia when treated 

 with alkalies. (Robiquet.) The juice of the fresh tobacco leaf 

 contains ammoniacal salts. The water which exudes from a cut 

 vine", when evaporated with a few drops of muriatic acid, also 



