From the 'Rosen-Zeitung' 1893, page 98:

"Neuste Rosen für 1894.
Züchter: Soupert u. Notting.

Comte Francois Thun. Strauch kräftig, niedrig, buschig, Blume gross, gefüllt, schalenformig, Knospen schön geformt, beim Aufblühen sammtigbraun; die Farbe der Blumen amarant blutrot mit acajou nuanciert, in dunkelcarmin übergehend. Wohlriechend. Die dunkelste der Theerosen (Madame Lombart x Alph. Karr.)"

My translation:

Newest roses for 1894.
Breeder: Soupert & Notting.

Comte Francois Thun. Bush vigorous, low, bushy, flower large, double, shallowly cupped, buds beautifully formed, velvety brown on opening; the colour of the flowers amaranth blood-red nuanced with cashew, shaded with dark carmine. Well scented. The darkest of the Tea Roses (Madame Lombart x Alph. Karr.)

["acajou" literally is cashew but can be translated as mahogany as well. Mme "Lombart" is spelt that way in the original. Francois is written in the original text with a cé cédille, but my computer can't do that]