328 AMMONIA AND NITRIC ACID. 



were burned, a certain quantity of nitrite of ammonia 

 was always formed, together with water and carbonic 

 acid. Almost contemporaneously with this notice, I 

 received from Schonbein a written communication an- 

 nouncing the very same results which he had obtained in 

 the same way, so that no doubt can remain as to the 

 correctness of this fact. 



The practical farmer, who is really anxious to improve 

 his method of cultivation, must be led by these un- 

 doubted facts to determme upon ascertaining, with the 

 greatest clearness, the effect of nitrogen in his manures. 

 Before he has been convinced that the atmosphere and 

 rain convey the necessary amount of nitrogenous food to 

 his plants, no one could expect him to renounce the 

 employment of ammonia as a manure. When it is as- 

 serted that the farmer can give a maximum of fertility 

 to his land without supplying to it any nitrogenous 

 matter, it is not meant that he must renounce the use of 

 farm-yard manure ; but the assertion implies the existence 

 of the latter, and is, in fact, based upon it. 



For the restoration or augmentation of productive 

 power in exhausted corn-fields, it is absolutely necessary 

 that the arable soil should contain a surplus of all nutri- 

 tive substances for cereal plants, nitrogenous among 

 others, but no one in greater proportion than the rest. 

 It is assumed that the farmer by a right succession of 

 crops, that is, by a proper proportion between his corn 

 and fodder fields, is always in a position, by carefully 

 husbanding the ammonia in his farm-yard manure and 

 avoiding all unnecessary waste, to provide the arable soil 

 with such a surplus of nitrogenous food as will corres- 

 pond to the proportion of the other nutritive substances 

 therein stored ; and that the atmosphere annually makes 

 up what he removes in his crops. 



The nitrogenous food conveyed by the atmosphere and 



