In Chinua Achebe's 'An Image of Africa: Racism in Conrad's 'Heart of Darkness' (1977), the Nigerian writer points to Conrad's 'inordinate love' of the word nigger as evidence that he had 'a problem with niggers.'
It would be untrue to claim that the word was considered any less offensive in Conrad's day than it is today. The entry in the Oxford English Dictionary (composed around the time Heart of Darkness was published) defines nigger as 'a negro (colloq. and usu. contemptuous).' Gilbert Murray, writing in 1900, declared the word obsolete except in South Africa, where it was 'still used very much in the old [pejorative] sense.'
Conrad would certainly have been aware of the derogatory sense of the word through his close friendship with R. B. Cunninghame Graham, whose 1897 essay 'Bloody Niggers' makes clear that for most British conservatives at the turn of the century nigger was a term of contempt applied generally to 'all those of almost any race whose skins are darker than our own, and whose ideas of faith, of matrimony, banking, and therapeutics differ from those held by the dwellers of the meridian of Primrose Hill.' However, 'in consideration of the 'nigger' races which God sent into the world for whites (and chiefly Englishmen) to rule, 'niggers' of Africa occupy first place.' Conrad had also remarked to Ford Madox Ford that the French showed less prejudice in their colonising activities because 'they had none of the spirit of Mr. Kipling's 'You Bloody-niggerisms' about them.'
Peter Edgerly Firchow suggests that the use of the word in the novel reflects the racist language of the Merchant Navy, where Conrad had first learned to speak colloquial English. 'As a nonnative speaker of English,' Firchow claims, 'Conrad may have been attempting to convey in this way what he perhaps thought was a "natively" English impression.'
Peter Edgerly Firchow, Envisioning Africa: Racism and Imperialism in Conrad's Heart of Darkness (2000)
Frances B. Singh, 'The Colonialistic Bias of Heart of Darkness' (1978)
Cedric Watts, ' "A Bloody Racist": About Achebe's View of Conrad' (1983)