EXISTENCE OF AMMONIA IN THE JUICES OF PLANTS. 45 



Any one may satisfy himself of the presence of ammonia in 

 rain by simply adding a little sulphuric or muriatic acid to a 

 quantity of rain-water, and by evaporating this nearly to dryness 

 in a clean porcelain basin. The ammonia remains in the residue, 

 in combination with the acid employed ; and may be detected 

 either by the addition of a little chloride of platinum, or, more 

 simply, by a little powdered lime, which separates the ammonia ; 

 and thus renders sensible its peculiar pungent smell. The sen- 

 sation perceived upon moistening the hand with rain-water, so 

 different from that produced by pure distilled water, and to which 

 the term softness is vulgarly applied, is also due to the carbonate 

 of ammonia contained in the former. 



The ammonia removed from the atmosphere by rain and other 

 causes, is as constantly replaced by putrefaction of animal and 

 and vegetable matters.* A certain portion of that which falls 

 with the rain evaporates again with the water ; but another por- 

 tion is, we suppose, taken up by the roots of plants, and entering 

 into new combinations in the different organs of assimilation, 

 produces, by the action of these and of certain other conditions, 

 albumen, gluten, and vegetable casein, or quinine, morphia, 

 cyanogen, and a number of other compounds containing nitrogen. 

 The chemical characters of ammonia render it capable of enter- 

 ing into such combinations, and of undergoing numerous trans- 

 formations. 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 azotised 

 matters contained in them. This question is susceptible of easy 

 solution by well-known facts. 



In the year 1834, I was engaged with Dr. Wilbrand, professor 

 )f botany in the University of Giessen, in an investigation re- 

 in well-water, for they have often to reject as much as one-fourth of the 

 water distilled, before they procure water which is not rendered turbid by 

 corrosive sublimate. But when phosphoric acid or alum is added to the 

 water previous to distillation, the product of the distillation is not affected 

 either by corrosive sublimate or by sugar of lead. (Wiegmann and Pot- 

 storf's Prize Essay on the Inorganic Ingredients of Plants.) 



* " We cannot doubt," says Saussure, " that ammonia exists in the atmo- 

 sphere, for we know that sulphate of alumina is gradually converted int< 

 •mmoniacal alum by exposure to the air " (Rech. stir la Vigit.) 



