Note P — Chapter XVIII

The bitumen most suitable is that variously known as Syrian asphalt, Jew’s pitch and bitumen of Judea. This is finely powdered and placed in a bottle with twice the bulk of ether and occasionally agitated for five hours, at the end of which time the ether may be poured off and fresh supplies added so long as any portion soluble in the ether remains. The purified residuum maybe dried and dissolved in benzole or chloroform; this will yield a solution which may be used as above, but poisoning, perhaps, twenty times its sensitiveness. The picture is developed with turpentine.