Cape Dopp

Brandy has a long history in South Africa, with the first distillation being recorded in 1672. The Dutch, inventors of brandewijn, naturally brought their stills with them, although the resulting brandy was pretty rough. For two centuries the Dutch produced only a particularly fierce form of marc known variously as dop (short for dopbrandewyn, or husk brandy), Cape smoke, or witblits (an Afrikaans word meaning white lightning).  

Lowry refers to the drink in his short story 'Seductio ad Absurdum'; "And it wasn't wine at all but Cape Dopp, wot we call Cape Dopp— raw spirit gawd blimey. Why, do you know, we all went mad, mad, and they had to tie Deaffy up to the bullock post." (Pg. 9) and "Fellers used to keep em as pets and make em drunk on Cape Dopp." (Pg. 9); these lines are repeated in his first novel Ultramarine (Pgs.127-128) 

Lowry's possible source for knowledge of the drink is most likely The Dop Doctor by Richard Dehan (1910)," being the native name for the cheapest and most villainous of Cape brandies, has come to signify alcoholic drinks in general to men of many nations dwelling under the subtropical South African sun. Thus, apple-brandy, and peach liqueur, "Old Squareface," in the squat, four-sided bottles beloved no less by Dutchman and Afrikander, American and Briton, Paddy from Cork, and Heinrich from the German Fatherland, than by John Chinkey—in default of arrack—and the swart and woolly-headed descendant of Ham, may be signified under the all-embracing designation." (Pg. 99). Lowry also uses the phrase 'Old Squareface' in Ultramarine when the quartermaster on board Oedipus Tyrannus asks Dana to his cabin for a drink; "Come along to my room and have a slice of old squareface." (Pg. 37).