In cutting off the loose bark, the edges should be made smooth before the coal tar is applied.
When dry, the outer layer of cement should be covered with coal tar to prevent cracking.
From there he went on to study the chemistry and technology of dye making, most especially to attempt a general classification of coal tar dyes for staining purposes.
It is only a product of coal tar.
Natural phenol is a product of coal tar, which is a by-product of the carbonisation of coal.
Complete particulars of the output of coal tar in this country are not available.
During the same period the registered imports of coal tar amounted to 3,065 tons.
Over a period, the water combines with the coal tar pitch to produce chemicals known as polycyclic aromatic hydrocarbons.
