390 STATE BOARD OF AGRICULTURE. 



of peat and liiimns to be present in the form of protein or its decom- 

 position products. Protein bodies themselves are readily destroyed by 

 bacteria and some of the resulting substances contain nitrogen in a 

 form that is easily absorbed by plants. Were all the nitrogen in peat in 

 this form, it would seem highly probable that peat would be very effi- 

 cient as a nitrogenous fertilizer. As is well known, however, such is 

 not the case, which might indicate that during the progress of decay 

 either the protein bodies have been decomposed and to a large extent 

 removed or have been so changed as to render their nitrogen unfit for 

 plant food. "While several amino acids have actually been isolated 

 from peat, still in most cases the largest part of the nitrogen seems to 

 consist of non-protein bodies, the chemical nature of which cannot as 

 vet even be surmised. 



It might seem, from the above discussion, that the isolation of these 

 bodies should cause but little trouble, but in reality it has not proved 

 so, and only within the last few years has the isolation of an individual 

 organic nitrogenous compound been accomplished. 



Previous Investigations. 



One cannot help but be impressed with the amount of time which 

 has been vainly spent in attempts to isolate some such compound in 

 the pure condition. For years chemists have been extracting peat 

 soils with alkali, precipitating from such extracts by means of acids, 

 dark-colored amorphous substxmces, analyzing them, and claiming for 

 them the characteristics of definite chemical compounds. So weak have 

 been the foundations of these claims that until very recently none has 

 stood the tests of later investigation. Perhaps the most noticeable 

 feature about the experiments has been the uniformity of the general 

 method of procedure by which each successive investigator has attacked 

 the problem. By far the greater part have treated the soil with a 

 solution of alkali or alkaline carbonate, precipitated from this solution 

 the characteristic dark brown, flocculent substance, and then either 

 analyzed this directly or first purified it by resolution and reprecipita- 

 tion with acid or some arbitrary precipitant, such as lead acetate. 

 The result has invariably been the same, a substance whose percentage 

 composition differed from all of its predecessors and one which later 

 investigators could not duplicate. Rarely were the researches carried 

 beyond the ultimate analyses of these substances or their socalled salts, 

 as the precipitates which they formed with various metallic salts were 

 supposed to be. Until quite recently, few experiments were made from 

 which any conclusion could be drawTi as to the structural composition 

 of the substances in question. They were simply nitrogenous compounds, 

 if compounds they were at all, and, until the last twenty-five years but 

 little attention was paid to the nitrogen radicle, although from tlie 

 standpoint of agricultural utility this is of the highest importance. 

 During the last few years, however, the study of the nitrogenous com- 

 pounds of peat and humus has been carried on in a more scientific man- 

 ner and we may safely say that more progress has been made than 

 during the entire preceding history of the work. 



The first worker to study the subject of peat humus was Einhof.^ 



"■'"Neues allgemeines Journ. d. Chem. 6, 381 (1805). Gmelins' Handbook of chem., trans, by Watt, 

 1866. p. 459. 



