NITRIFICA TION. 8 3 1 



at Dorpat, St. Petersburg, and Moscow ; of Brussels, where the little 

 Belgian state has made liberal expenditures for its iguanodons, ino- 

 sosauri, and hainosauri ; and of Haarlem, in Holland, where the Jeyler 

 Museum is being enriched every year with new paleontological curi- 

 osities ; of Switzerland, which is not behind any country in the zeal 

 with which it cultivates science ; and of Italy, where science has its 

 share in the revival which all departments of the intellectual life are 

 enjoying. But I have said enough to show that paleontology is culti- 

 vated and held in high regard in Continental Europe, and that we 

 Frenchmen also should not be indifferent to the questions of the 

 origin and development of life. Translated for the Popular Science 

 Monthly from the Revue Scientifique. 



* 



NITRIFICATION. 



Br Professor H. P. AEMSBY. 



THE production of nitrates during the decay of nitrogenous organic 

 matter under suitable conditions of moisture, aeration, and tem- 

 perature, is a reaction of no little importance both technically and 

 agriculturally : technically, as the sole natural source of saltpeter ; 

 agriculturally, on account of the fact that the nitrates formed in the 

 soil constitute the chief if not the only supply of nitrogen to the 

 plant. But, while the conditions of nitrification have long been well 

 known, it is only within the past eight or nine years that its true cause 

 has been recognized. Pasteur, in 1862, appears to have first pointed 

 out the similarity of nitrification to the various oxidations of organic 

 matter known to be effected by the agency of mycoderms, and of which 

 the acetic fermentation is the typical example. 



In 1873, A. Muller* advanced the opinion that nitrification was 

 due to the action of a ferment. He based his opinion the fact upon 

 that solutions of pure ammonium salts and of urea are very stable, 

 while the same bodies in sewage are rapidly nitrified, holding that the 

 difference was due to the presence of a ferment in the latter case. In 

 1877 Schloesing and Muntz \ published the results of experiments which 

 indicated that Pasteur's suggestion and Miiller's opinion were correct, 

 and that nitrification might really be classed as a fermentation. These 

 experimenters were engaged in investigating the oxidizing effect of 

 the soil upon sewage. They filled a glass tube one metre long with a 

 mixture of quartz, sand, and a small quantity of powdered limestone, 

 and caused sewage to filter slowly through this artificial soil, so that 

 it occupied eight days in passing through the tube. For twenty days 

 the sewage passed through unaltered. Then nitrates began to appear 



* " Landw. Versuchs-Stationen," xvi, p. 273. f " Comptes Rendus," lxxxiv, p. 301. 



