Marine glue is made from 1 part of Lndiarubber (cut into shredsi and 12 parts of coal-tar naphtha; these are kept in a bottle in a warm place and shaken from time to time till the rubber is dissolved; then 20 parts of powdered shellac are added, and shaking is continued until the mass becomes pasty. It is then poured on to a cold surface, allowed to solidify, and then broken up into small pieces, which should be melted and applied as thinly as possible while still warm. Great care must be taken in making this cement, as the naphtha is very inflammable.