92 SOURCE AND ASSIMILATION OF NITROGEN. 



Hiinefield has proved that all the springs in Greifs- 

 walde, Wick, Eldena, and Kostenhagen, contain car- 

 bonate and nitrate of ammonia. Ammoniacal salts 

 have been discovered in many mineral springs in 

 Kissingen and other places. The ammonia of these 

 salts can only arise from the atmosphere. 



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-wafer, and 

 evaporating this nearly to dryness in a clean porce- 

 lain 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 

 its peculiar pungent smell sensible.* The sensation 

 which is 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.f 



The ammonia which is removed from the atmo- 

 sphere by rain and other causes, is as constantly re- 

 placed by the putrefaction of animal and vegetable 

 matters. A certain portion of that which falls with 

 the rain evaporates again with the water, but another 

 portion is, we suppose, taken up by the roots of 

 plants, and, entering into new combinations in the 

 different organs of assimilation, produces albumen, 

 gluten, quinine, morphia, cyanogen, and a number 

 of other compounds containing nitrogen. The chem- 

 ical characters of ammonia render it capable of 



* Since the appearance of the first edition, this experiment has been 

 repeated by many in France, Germany, America, and England, and the 

 existence of ammonia in the atmosphere has been completely confirm- 

 ed. The assertion, that this ammonia possesses the "offensive smell 

 of perspiration and animal excrements," has been ridiculed by many 

 as fanciful, — by none, however, who have made the experiment. The 

 experiment is so exceedingly easy to perform, that any one may con- 

 vince himself of the accuracy of the statement. — Ed. 



t A small quantity of ammonia toater, added to what is commonly 

 called hard water, will give it the softness of rain or snow water. 



