Why did equiano find himself in a different position than other enslaved people?

In the book he wrote, Equiano displayed his belief that free blacks often suffered worse conditions than slaves. In the West Indies, he met a free black man whose name was Joseph Clipson. Clipson's story was the basis of his realization. Clipson had freedom but was aggressively spoken to by a Bermuda captain who insisted that Clipson was a slave and that he had to take him to Jamaica. Clipson protested but he was ignored and was forced to go aboard the captain's ship. Equiano wrote on his book that he had thought only slavery was dreadful, but the condition of a free negro was just as equally so. Their freedom was minimal and they lived in fear of constant abuses. There were no courts to listen to them and no law would protect their properties. When Equiano became a free black, he also encountered the same situation. Free blacks lived in an uncertain middle ground between slavery and freedom. 

What is the

He droped it over the bridge into the river