Primage

noun

1. A small sum of money formerly paid over and above the freight to the master of a ship for his care of the goods: now charged with the freight and retained by the ship-owner. Also called hat-money.
2. The amount of water carried over in steam from a steam-boiler by foaming, lifting, and atomizing of the water. See priming.
3. A duty of one per cent. imposed by the Victorian Parliament 1803–95, on the prime, or first entry of goods.
4. A charge in addition to the freight; originally, a gratuity to the captain for his particular care of the goods (sometimes called hat money), but now belonging to the owners or freighters of the vessel, unless by special agreement the whole or part is assigned to the captain.
5. Droplets of water suspended in steam (especially in the cylinder of a steam engine).