EXISTENCE OF AMMONIA IN THE JUICES OF PLANTS. 93 



entering into such combinations, and of undergoing 

 numerous transformations. We have now only to 

 consider whether it really is taken up in the form 

 of ammonia by the roots of plants, and in that form 

 applied by their organs to the production of the 

 azotized matters contained in them. This question 

 is susceptible of easy solution by well-known facts. 



In the year 1834, I was engaged with Dr. Wil- 

 brand, Professor of Botany in the University of 

 Giessen, in an investigation respecting the quantity 

 of sugar contained in different varieties of maple- 

 trees, which grew upon soils which were not ma- 

 nured. We obtained crystallized sugars from all, 

 by simply evaporating their juices, without the ad- 

 dition of any foreign substance ; and we unexpected- 

 ly made the observation, that a great quantity of 

 ammonia was emitted from this juice when mixed 

 with lime, and also from the sugar itself during its 

 refinement. The vessels which hung upon the trees 

 in order to collect the juice were watched with 

 greater attention, on account of the suspicion that 

 some evil-disposed 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 w^ood 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 crystalli- 

 zation. Every person who has entered such a manu- 

 factory must have been astonished at the great 

 quantity of ammonia which is volatilized along with 

 the steam. This ammonia must be contained in the 

 form of an ammoniacal salt, because the neutral 



