458 [AssembKS 



receive food from the atmosphere in the shape of gases. I ha^ 

 grown plants, and brought them to full fruit-bearing perfectiol^ 

 in fine charcoal dust, exposed to atmospheric influence, and raSl 

 water. It yields to plants silicate of potash and other salts, b^ 

 sides condensed gases, such as carbonic acid, &c. This is tj[> 

 most unchangeable of all known substances, I experimented 

 with it many years since, and believe myself to be the first wtS) 

 used it for agricultural purposes. The atmosphere contains tl^ 

 principal food of plants, in the shape of carbonic acid gas. Dt^ 

 ring the growth of plants, they appropriate carbon in the form cSf 

 carbonic acidj and in the process of decay, emit it in proportic^jD 

 to the quantity of oxygen they contained. Without nitrogeli^ 

 plants would not grow even in the richest soil, as every part ol 

 their structure contains it. The question is then asked, ho|r 

 nature furnishes so large a quantity, and In what form 1 Niti^ 

 gen of the air will not combine with any element except oxyg^ 

 It is supposed that there are 1,000,000,000 of persons in t]^ 

 world, and that a whole generation passes away every thirfjr 

 years. During that period, tens of thousands of millions of an^ 

 mals die. They all contained nitrogen, and during their dec^ 

 gave it up to the atmosphere, in the shape of ammoniacal gas, th|S 

 substance will rise from the depth of fifty or sixty feet, and is t5> 

 most simple of all the compounds of nitrogen. Every shower £9? 

 rain, meeting with this ammonia in the air, condenses it, and coj^ 

 veys it to the earth's surface, where it renders humus solubI|) 

 and fits it for the assimilation of plants. It is as well to sta|fe 

 that when ammonia is extracted from rain water or snow, & 

 gmells like the perspiration emitted by animals, which givefi » 

 hint of its origin. 



Therefore it is ammonia which afiords nitrogen to the vege^ 

 ble, and forms the blue and red coloring substances contained Eb 

 flowers, and by one of its transformations gives nitric acid to t]^ 

 sunflower and tobacco. The solid excrements of animals conta&i 

 a small percentage of nitrogen, but the liquid a very large quaS^ 

 tity. The chief reason why gypsum has such a good effect upd|i 

 clovers, &c., is that it attracts and fixes the ammoniacal gassi 

 floating in the atmosphere, in the soil ; 220 lbs. of burned gyp- 

 sum or chloride of calcium, will fix as much ammonia in the sop 



