AMMONIA AND NITRIC ACID. 



The returns obtained by manuring with the salts of 

 ammonia were the following : 



It is easy to see that the expectations which had 

 been founded upon the deep dark-green colour were 

 not realised. The salts of ammonia were so far from 

 exerting any influence in augmenting the corn-crop, 

 that they diminished it in every experiment. In the 

 crop of straw there was a small increase. 



In these cases the salts of ammonia had not enlarged 

 the corn crop, but had produced the opposite effect 

 from guano, by which corn crops are generally aug- 

 mented. 



These experiments cannot, however, be regarded as 

 decisive proofs against the view of the action of ammo- 

 nia, because a comparative experiment with guano was 

 not made at the same time and place. It is not impos- 

 sible, that upon this particular field guano might have 

 produced the same results. Some years later, Lawes 

 and Gilbert published a series of investigations, which 

 seemed to establish the operative power of ammonia, or 

 rather of salts of ammonia. These investigations were 

 intended to show, that the incombustible nutritive sub- 

 stances of wheat were not, of themselves, sufficient to 



