56 



now CROPS FEED 



by plants as food is most abundantly established. The 

 salts of ammonia applied as manures in actual farm prac- 

 tice have produced the most striking effects in thousands 

 of instances. 



By watering potted plants with very dilute solutions of 

 ammonia, their luxuriance is made to surpass by far that 

 of similar plants, which grow in precisely the same condi- 

 tions, save that they are supplied with simple water. 



Ville has stated, 1851-2, that vegetation in conserva- 

 tories may be remarkably ])romoted by impregnating the 

 air with gaseous carbonate of ammonia. For this purpose 

 lumps of the solid salt are so disposed on the heating ap- 

 paratus of the green-house as to gradually vaporize, or 

 vessels containing a mixture of quicklime and sal ammo- 

 niac may be employed. Care must be taken that the air does 

 not contain at any time more than four ten-thousandths 

 of its weight of the salt ; otherwise the foliage of tender 

 plants is injured. Like results were obtained by Petzholdt 

 and Chlebodarow in 1852-3. 



Absorption of Ammonia by Foli- 



aj^C. — Although such facts indicate 

 that ammonia is directly absorbed by 

 foliage, they fail to prove that the 

 soil is not the medium through which 

 the absorption really takes place. We 

 remember tliat according to Unger 

 and Duchartre Avater enters the 

 higher plants almost exclusively by 

 the roots, after it has been absorbed 

 by the soil. To Peters and Sachs 

 ( Chem. Ackersmann, 6, 158) we owe 

 an experiment which appears to de- 

 monstrate that ammonia, like carbonic 

 acid, is imbibed by the leaves of 

 I' iy: ^'- plants. Tlie figure represents the ap- 



paratus employed. It consisted of a glass bell, resting below, 



