check out our:
"I had no idea of the conditions, he [the harlequin] said: these heads were the heads of rebels. I shocked him excessively by laughing. Rebels! What would be the next definition I was to hear? There had been enemies, criminals, workers—and these were rebels. Those rebellious heads looked very subdued to me on their sticks." (3.6)
Add "language" to the list of things that don't quite hold up to close inspection. The white men have called the Africans "enemies, criminals, workers" and now "rebels"—which is especially ridiculous, because the Africans haven't been allowed nearly enough power or freedom of choice to be called such things. (But it sure does make sticking their heads on sticks a lot more justifiable.)
"'He [the harlequin] suspected there was an active ill-will towards him on the part of these white men that—.' 'You are right,' I said, remembering a certain conversation I had overheard. 'The manager thinks you ought to be hanged.'" (3.21)
The manager's racism extends towards Russians as well. He wants to kill the harlequin simply because he's different from the others. That, or maybe he just doesn't like the guy's silly clothes.
[When leaving the Inner Station with Kurtz]: "In front of the first rank, along the river, three men, plastered with bright red earth from head to foot, strutted to and fro restlessly. When we came abreast again, they faced the river, stamped their feet, nodded their horned heads, swayed their scarlet bodies; they shook towards the fierce river-demon a bunch of black feathers, a mangy skin with a pendant tail—something that looked like a dried gourd; they shouted periodically together strings of amazing words that resembled no sounds of human language; and the deep murmurs of the crowd, interrupted suddenly, were like the responses of some satanic litany." (3.30)
White men view the native Africans as "savages" in their paint and armed with their strange weapons. Their language is so alien that it sounds like a "satanic litany." Which, unless it says "here's to my sweet Satan" when played backwards, sounds like a stretch to us.