294- ANNUAL OF SCIENTIFIC DISCOVERY. 



from solution in water, to the existence of a class of double silicates of alumina 

 and another base, which is generally lime or soda. Mr. "Way has succeeded, 

 for the first time, in producing this class of salts ; and he argues, from the 

 effects observed in soils, that these latter contain the silicates in question in 

 small quantity, and hence their power to preserve soluble manures from loss 

 by rain and drainage. His second paper on this subject refers to the action 

 of lime on soils, and he endeavors to show, from the large quantity of 

 ammonia existing in almost all soils, which, according to his experiments, 

 very far exceeds the doses of this alkali usually applied in manure, that lime 

 acts much in the same way as ammoniacal manures themselves, by famishing 

 indirectly a supply of nitrogen to plants. The effects of over-liming are 

 accounted for in the same way. 



The subject in the chemistry of agriculture, which has lately, however, 

 attracted the greatest share of attention, both in this country and abroad, 

 is that of the source from which plants derive their nitrogen. It has been 

 satisfactorily proved that plants growing in the ordinary way often contain 

 more of the element nitrogen than they can obtain from the soil in which 

 their roots are placed ; and it is obvious that in some way or other this accu- 

 mulation is derived from the atmosphere. Now, the air surrounding the 

 globe is composed of a mixture of nitrogen and oxygen gases in the proportion 

 of about four parts of the former to one part of the latter ; it also contains 

 small quantities of other gases, such as carbonic acid, nitric acid, and ammo- 

 nia. The question at issue is, as to whether plants can, under any circum- 

 stances, make use of the great bulk of the nitrogen of the air in building up 

 their tissues, or whether they derive the observed excess from the ammonia 

 and nitric acid of the air. This question, the interest of which, both in a 

 purely scientific and agricultural point of view, can hardly be overrated, has 

 enlisted the energies of chemists on both sides, and has given rise to some 

 admirable researches. It has also involved the extended examination of air 

 and rain water, in order to ascertain how much ammonia and nitric acid are 

 usually contained in the one, and brought clown by the other. The principals 

 in this discussion in France are MM. Boussingault and Ville ; both of these 

 chemists have made extended series of experiments on plants grown in glass 

 cases ; then- conclusions are, however, diametrically opposite : M. Boussingault 

 contending that plants cannot make use of the atmospheric nitrogen, but must 

 be indebted to the nitric acid and ammonia in the air for their supply in 

 excess over that furnished by the soil : M. Ville maintaining that in the 

 absence of both of these, an increase of nitrogen in plants still takes place. A 

 Commission of the French Academy of Sciences, recently appointed to look 

 into this matter, leans rather in its report to the side of M. Yille, but the 

 question is still far from being set at rest. 



M. Barral has determined the quantity of ammonia and nitric acid brought 

 down by rain in Paris. M. Boussingault has repeated these experiments as 

 regards ammonia in Alsace, and finds the quantity very much smaller than in 

 the rains of the city, a circumstance which we should be prepared to expect. 

 M. Boussingault has also examined, with the same object, the water of 

 fogs, and dew, and of rivers and streams. M. Ville has carefully deter- 



