The lithograhy technique is very similar to pencil drawing on paper. It is based on the chemical properties of the lithographic stone, a carbonate of fine grained calcium.
Using a pencil or brush the lithographer covers the carefully polished stone in black. Having applied a light chemical fixer, the stone is then moistened. The ink when passed through a roller, will stick only to the drawing, which remains in bold and leaves the moist, blank parts of the stone in white. All that remains is to place a sheet of paper on it and then send everything to the printing press.

"...Do you not know the fonds d’Arquet?" A marvel! Just imagine, as I am on my way there, I meet a funeral. I have always had a weakness for funerals. In Namur, the coffin is usually carried and the bearers wear black capes with yellow collars, inherited from the Spanish, pretty splashes of colour against the grey backdrop of the roads. This one was a particularly sad funeral. It is rare. The coffin, draped in rich cloth decorated with skulls of pure gold, was followed by a little blonde boy, the dull blonde that is born of recreation breaks without fresh air and a hundred lines as punishment for a smile! It was he, the poor little fellow, who was leading the mourners, with his little red nose and big tears through his lashes. Walking at his side, a dignified and protective gentleman, probably an uncle or legal guardian. The gentleman was also in full mourning and having put on some weight, was wearing the suit that he only wore on the day of the Te Deum for the Royal Jubilee or for the Governor’s party.
A gouty priest, with his stockings falling around his ankles, two priests chanting, gloomily grotesque; with red complexions from their troubled digestion; a verger with cotton wool in his ears, one male and one female member of some congregation, an altar boy and a dog; that was it. At the cemetery an old gravedigger, with a liking for a drop of strong drink. All this mumbling did not lack for a certain gloomy and sinister comedy, beneath a grey autumn sky where sudden bursts of sunlight shone brighter than the the blue white of the surplices . During the oration the altar boy splashed the dog and the pall bearers drank. I liked this scene and decided to draw it on a big lithographic stone..."
Letter from Rops to Charles De Coster