A physician feeling the forehead of a child in Dalarna, Sweden. Heliogravure after F. Rops.

In 1874 Rops travelled to Sweden where, according to a letter from him dated 18 July 1883, he experienced the symptoms of a disease called "blue fire", apparently a disease akin to malaria or a rickettsial disease. He says in the letter that he was cured by a priest of Finmarck (in the north of Norway): "jai été guéri par un prêtre du Finmarck qui pour toute panacée m'avait saturé d'eau de vie de bouleau & m'avait fait transpirer pendant dix heures sous vingt peaux de renne. On est sauvé ou on est mort". However Finmarck in Norway is nowhere near Dalarna in Sweden: the whole episode may be fictitious