18 JOURNAL OP* THE 



carbonate or wood ashes were absolutely necessary anH , 

 contrary to all oxidation processes, a limited supply of 

 air g-ave the best results. Carbonates evidently aided 

 in some way, probably in decomposing* the org'anic mat- 

 ter, but rapid decay hindered the process, and in com- 

 bustion, which is more rapid oxidation, the production 

 of nitrates was indeed very small. So that chemists 

 puzzled over this apparently inexplicable question for a 

 long- time before a true sug'g'estion was offered. 



It is only within the past twenty years that a satis- 

 factory theory has been advanced and only within the 

 past three or four years, after the most careful and 

 painstaking" experiments by some of the most eminent 

 phvsiolog-ical chemists has the theory been accepted. 



A. Muller (Landw. Versuchs-Stat, lb, 273. Jour. 

 Chem.Soc. 1873, 1267) observing* the rapidity with which 

 the ammonia of sewerag-e and certain waters chang-ed to 

 nitrates and that pure solutions of urea and ammonium 

 compounds were not susceptible to this chang-e, sug*- 

 g-ested that it was due to the action of ferments. The 

 truth of MuUer's sug-g-estion was first shown by the 

 labors of Schloesing* and Muntz (Conipt. Rend. 85, 

 1018). They studied the action of heat upon the pro- 

 cess and soon found that varying- temperatures exerted 

 a remarkable influence. A temperature of 100°C. for 

 one hour was sufficient to destroy the nitrifiable power 

 of certain soils and veg^etable moulds in which nitrifi- 

 cation was known to be most actively taking- place. 

 The addition of a little unheated mould however, served 

 to again start the process. This was very strong- evi- 

 dence that nitrification was in some way connected with 

 org-anized life. A powerful microscope revealed to 

 them the existence of numerous org-anisms of the most 

 varied kinds, being- most abundant in veg-etable mould. 



