In later years, the political influence of the West Indian planters led to rum being given the preference over prove its strength by checking that gunpowder doused with rum would still burn (thus verifying that rum was at least 57% ABV).
In later years, the political influence of the West Indian planters led to rum being given the preference over arrack and other spirits. The half pint of spirits was originally issued neat; it is said that sailors would "prove" its strength by checking that gunpowder doused with rum would still burn (thus verifying that rum was at least 57% ABV).