Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Used in treatment of psoriasis.
DEFINITION
Tar is bituminous liquid obtained from the wood of various trees of the family Pinaceae by destructive distillation and is known in commerce as Stockholm Tar.
CHARACTERISTICS
Dark brown or nearly black, semi-liquid; denser than water.
Soluble in ethanol (90%), in ether and in fixed and volatile oils.
IDENTIFICATION
A. The aqueous liquid obtained by shaking 1 g with 20 mL of water for 5 minutes is acidic to litmus paper.
B. Carefully add 0.5 g to 10 mL of petroleum spirit (boiling range, 40° to 60°) and allow to stand for 30 minutes. When examined in daylight no fluorescence is produced.
