1905] TRANSEAUBOGS OF THE HURON RIVER VALLEY 375 



hydrates. These bodies not only occur in nature, but may be arti- 

 ficially produced by the action of strong acids on starch, sugar, and 

 cellulose. The relation of nitrogen to these bodies is still unknown. 

 Principally on the basis of color and solubility in alkalies and acids, 

 there are several substances distinguished. Ulmin and ulmic acid 

 are brown, and are early products of decomposition. Humin and 

 humic acid are black, and occur more abundantly where eremacausis 

 has been active for a long time. Crenic and apocrenic acids appear 

 to be further oxidation products; the former is colorless, and the 

 latter varies from yellow to brown. MAYER believes these bodies to 

 be organic nitrogen compounds (36), and on this basis STOCKBRIDGE 

 (50, p. 135) explains the insolubility of peat soils and the presence of 

 the unavailable nitrogen in peat. Beside these substances xylic, 

 saccharic, and glucinic acids have been recognized. Although great 

 advances have been made in soil chemics, it seems strange that the 

 only suggestion of formulae for these substances was made by MULDER 

 in 1861 (38). 



Humic acid forms water-soluble compounds with the alkalies, and 

 to these are due largely the brown colors of the bog waters. The color 

 may be produced by the presence of free humic acid. With the 

 alkaline earths humic acid forms insoluble or difficultly soluble com- 

 pounds. Hence there is slight chance of lime and magnesia pene- 

 trating from the surrounding soil into the peat deposits. 



During the changes which the plant material undergoes in the 

 process of peat-making there are alterations in the relative amounts 

 of volatile hydrocarbons, fixed carbon, and ash using these terms 

 as in ordinary coal analyses. 



The proportion of volatile combustible matter decreases regularly 

 as the humification proceeds. The ash regularly increases, while the 

 air-dry water content shows but slight modification. . 



(To be continued.} 



