Green’s Dictionary of Slang

1. a derog. term for a black person.

1838		Hesperian (Columbus, OH) Dec. 117/1: The night was enlivened by the music of a cracked fiddle, in the hands of a negro lad, while two or three small sooties kicked up a dust about them .
1978		W. Donaldson Balloons in Black Bag 90: If the Major calls him darky, sooty, [...] skunk or Zulu to his face, we’re going to be short of a valuable new comedy act.
1986		Sun. Express (London) Mag. 28 Dec. 18/4: I am not racialist, but I can’t bear to watch the sooties any more – it’s like Uncle Tom’s Cabin.
1998		J. Hoskison Inside 109: Just a tolerance test with all these ‘sooties’.
2013		K. Sampson Killing Pool 9: We’ve got the sooty bang to rights.

2. a nickname given a chimney-sweep.

1882		(con. 1840s) Nat. Police Gaz. 21 Oct. 11/2: [Tom] Cribb observed to the sweep, ‘I say, Sooty, you have forgotten to mention what you mean to charge a bushel for your inferior soot.’ The sweep stamped and swore and was boiling with rage .
1896		Regiment 23 May 123: [cartoon caption] officer Why don’t you look where you are going you black rascal. sooty Garn, lobster, you were as black as me afore you was boiled.