Sentence:  One day, it is in February, 1731, as I compute, they are sitting, her Sonsfeld and she, at their sad mess of so-called dinner, in their remote uppoer story of the Berlin Schloss, tramp of sentries the one thing audible; and were "looking mournfully at one another, with nothing to eat but a soup of salt and water, and a ragout of old bones full of hairs and <WSD>slopperies</WSD> [nothing else; that was its real quality, whatever fine name they might give it, says the vehement Princess], we heard a sharp tapping at the window; and started up in surprise, to see what it could be. 
Meaning of the word marked with <WSD> tags:  Watery unappetizing food; gruel.