EESOURCES op NITEOGEN. 115 



II. 



NATURAL RESOURCES OF NITROGEN PLANT-FOOD, WITH REF- 

 ERENCE TO THEIR AGRICULTURAL VALUE. 



The air and the soil are the natural storerooms of ammo- 

 nia, nitrous and nitric acid. 



Beginning our inquiry with the air, we know from numer- 

 ous actual examinations, that it contains at all times small 

 quantities of ammonia, in combination with nitrous acid or 

 nitric acid, or in case both are wanting, with carbonic acid. 



Peculiar meteorological phenomena, as thunder-storms, are 

 known to affect the relative proportions of nitric acid and am- 

 monia ; whilst the season and the locality control their abso- 

 lute quantity. 



Densely populated districts show more than thinly settled 

 sections of the country. Long periods of dry weather tend 

 to increase their quantity in the air, whilst frequent rain-fall, 

 heavy dews, or snoAV-f\dl, diminish their amount by carrying 

 them into the soil. A few well supported statements of 

 observations referring to these points may convey some more 

 definite idea. 



Liebig noticed in 1826, for the first time, the presence of 

 nitric acid and ammonia in rain-water. 



Bineau and Barral, who, in 1852 ascertained at the astro- 

 nomical observatory at Paris the amount of nitric acid and 

 ammonia contained in the entire annual rain-fall, found it 

 consisting of twenty-senen kilogrammes of ammonia and 

 thirty-four kilogrammes of nitric acid per hectare, or twenty- 

 two pounds per acre. Observations at Nantes and Lyons 

 gave similar results. 



Boussingault, who had carried on similar tests during the 

 same year, upon his farm at Liebfrauenberg, in the Alsace, 

 found but one-seventh of Bineau and Barral's results; namely, 

 three and one half pounds of nitrogen per acre. 



Gilbert and Way, who made observations at Rothamstead, 

 in England, during the years of 1855 and 1856, found one- 

 third of Bineau's results, or between from seven to eight 

 pounds per acre. 



Kuop found at Moeckern (1860) in the month of July, 



