cxcii GENERAL SUMMARY OF SCIENTIFIC AND 



lime, that is, under circumstances which approach more nearly to 

 those which actually exist in cultivated soils. 



The Assimilation of Atmos^jheric Nitrogen and the Absorption of Am- 

 monia hy the Soil. The much-vexed question as to whether the soil 

 has the joower of assimilating free nitrogen is still in dispute. Si- 

 mon and Deherain claim to have proved the absorption of free ni- 

 trogen by organic compounds ; but Boussingault, in a long-contin- 

 ued experiment, found a loss rather than gain of nitrogen in the 

 soil, and Schloessing, on repeating Deh6rain's experiments, fails to 

 find any such absorption of nitrogen as the latter investigator re- 

 ported. Schloessing has made several series of experiments on the 

 absorption of ammonia by soils. In one series he passed air over a 

 trough containing three hectoliters of soil, determining the amount 

 of ammonia in the air before and after contact with the soil. There 

 was a considerable loss of ammonia, indicating that some had been 

 absorbed. 



In two other series of experiments small portions of soil were ex- 

 posed to the action of the air. In each parallel trials were made, 

 the soil in one being in open air and kept moist, while that in the 

 other was covered and dry. In all cases ammonia was absorbed, 

 and in part oxidized to nitric acid. The oxidation was, however, 

 much greater in the moist than in the dry soil. These experiments, 

 therefore, confirm the generally accepted view that soils absorb am- 

 monia from the air and transform it into nitric acid. Comptes-Ilen- 

 (Zms,LXXXII., 1105-1108, 1202-1204. 



Absorption of Free Nitrogen of the Air lij Organic Compounds. 

 Berthelot has shown that free nitrogen is absorbed by organic com- 

 pounds at the ordinary temiDcrature under the influence of the silent 

 electrical discharge. Benzene, oil of turpentine, marsh gas, acety- 

 lene, and moistened filter-paper absorbed nitrogen, producing com- 

 pounds all of which evolved ammonia on being heated either alone 

 or with soda-lime. The author suggests that similar processes may 

 take place in nature, and that consequently plants may be able to 

 assimilate nitrogen directly from the air. This assumption is direct- 

 ly opposed to the results of the best investigation upon the subject, 

 which indicate that the free nitrogen of the air is not assimilated by 

 plants. It would seem more probable that the absorption of free 

 nitrogen by humus, and by soils containing humus, which Simon 

 and Truchot claim to have observed, might be induced in the man- 

 ner described by Berthelot, The experiments named are certainly 

 valuable contributions to the solution of the much-vexed question 

 of the assimilation of free nitrogen. Comptes-Hendiis^ LXXXII., 

 1283, 1284, 1357-1360 ; LXXXIIL, 677-682. 



Ash of Hemp and BucTcwheat Plants. A quite extended chemical 

 examination of the ashes of the hemp and buckwheat plants is re- 



