8o 



THE SPIRIT OF THE SOIL 



where the deposits remain undisturbed for many 

 years, the stages are indicated by the increasing 

 Carbon content of the Humus from varying depths. 

 This was shown by Detmer (1871), who gives the 

 following figures : 



" Thus, in peat bogs the carbohydrates of decaying 

 organic matter may possibly pass through changes 

 very similar to those observed when sugar is heated 

 to a high temperature Sugar, Caramelan, Humic 

 acid, Humin, and finally Carbonization (peat coal). 

 The fact established by van Bemmelen (1900) that 

 Humic acid is a colloid body, which has the property 

 of uniting with certain radicles, explains the various 

 empirical formulae ascribed to Humic acid, and the 

 complex nature of Humus in general. But under- 

 lying this complexity there is the possibility of 

 finding in the series of sugar changes described above 

 two fairly definite groups of substances, which serve 

 as a basis for Humus formation, the Humic group 

 gradually merging into the Humin group." 



