The quantities of carbon in the residues before and after prolonged
boiling show that practically all the carbonaceous matter in the
Hagerstown loam was decomposed by this treatment and that only
from one-half to one-third of that contained in the Carrington loam
colloid and muck was digested. The matter decomposed, being
highly carbonaceous, is probably charcoal, while that unattacked
is, presumably, not charcoal. These assumptions are supported by
the fact that the carbon in the sample of Hagerstown loam, a soil
material containing a large quantity of charcoal, was practically all
oxidized. Furthermore, a test showed that finely ground, nearly
fresh charcoal was completely decomposed by prolonged boiling with
peroxide.