To produce turpentine, the new companies put the stump wood through a process known as "destructive distillation." This process had originated around 1904 in stump country near Hinckley, Minnesota and had been imported to Michigan, where several million acres dotted with pine stumps promised prosperity to enthusiastic investors.
Each cord of stump wood would yield turpentine and by-products with a value of $25.75.
The Swedish Forest Agency recommends leaving 15-25% of stumps for environmental reasons, since stump wood can act as a habitat for different fungi, mosses, bryophytes, and insects [10, 11].
where [CV.sub.afb] is calorific value, ash-free basis (20.5 MJ/kg dw ), AC is total ash content, dw basis, 2.444 is the enthalpy difference between gaseous and liquid water at 25[degrees]C MJ/kg, 8.936 is the molar mass ratio between water ([H.sub.2]O) and hydrogen ([H.sub.2]), [[H.sub.2]] is hydrogen content in stored stump wood (6.075 ), and MC is moisture content, wet basis.