118 



concentrated solution of potash, nitrogen was eliminated in the form of 

 ammonia or other volatile alkaliue compounds, at first very rai)idly, 

 then slowly, and afterwards very slowly and in amounts proportioned 

 to the lime of the action. It was concluded that there were in the soil 

 two distinct amide-like com])ounds, differing in the facility with which 

 they are transformed into ammonia. Besides the nitrogenous material 

 transformed into ammonia, a much larger portion was rendered soluble 

 in water, but a part of this latter gradually reverted to an insoluble 

 form. The residue of the soil after extraction by i)Otash, on treatment 

 with dilute acid, yielded still more ammonia and amide-like compounds. 

 Over nine tenths was thus rendered soluble by cither acid or alkali 

 or both. The tendency of the action of both acid and alkali was to 

 decom[>ose the nitrogenous compounds and to form products of lower 

 molecular weight. 



In conclusion, the authors add that these experiments show how 

 the insoluble nitrogen of humus compounds is gradually rendered 

 soluble and assimilable. While the action of the plant upon these 

 compounds in the soil is certainly not identical with that of the acids 

 and alkalis of the laboratory experiments, nevertheless the latter offer 

 certain grounds of comparison in the consideration of the chemical 

 processes induced by earthy carbonates aiul by carbonic acids, as well as 

 by the acids formed by the plants. The length of duration of these natu- 

 ral processes makes up for the slowness as compared with the more 

 energetic action of the mineral acids ami alkalis. That is to say, the 

 comparatively weak bases and acids which occur in the soil and are 

 elaborated by plants, tend to set free the nitrogen of humus, both that 

 of the vegetable matter of which it is iormed and that of the ammonia 

 which it absorbs from the air. It may be assumed that alkaline and 

 acid fertilizers, such as lime, ashes, and acid phosphates, serve a similar 

 purpose in rendering the nitrogen of the soil available to plants. — [W. 

 O. A.] 



The volatile nitrogenous compounds exhaled by arable soil, 

 Berthelot [Compt. rend., llli (IS'JI), p. 1!I5). — In continuation of previ-' 

 ous investigations the author made experiments with argillaceous 

 sands, or clays poor in nitrogen. These were placed in porcelain pots, 

 under bell glasses of 50 litres capacity. Arrangements were provided 

 for introducing water to moisten the soils and collecting the water 

 which condensed on the bell glass. A dish containing dilute sulphuric 

 acid was also placed under the bell glass to absorb the ammonia emitted 

 from the soil. The experiments continued from May to October, 5^ 

 months. During the tirst half of this time the soil was moistened occa- 

 sionally. The moisture which collected on the bell glass was removed 

 weekly and sulphuric acid was added to it to hold the ammonia. 

 During the remainder of tlie titne of the experiment the soil was not 

 moistened J it became dry and the moisture ceased to condense on the 



