Abstract: Cellulose-containing, optionally wood-containing materials which have been obtained using water-dispersible polyisocyanates which in turn have been prepared by reaction of the following starting components:a) modified polyisocyanates of the formula (I) ##STR1## in which: R.sup.1 denotes an aliphatic hydrocarbon radical having 2 to 18 carbon atoms; a cycloaliphatic hydrocarbon radical having 4 to 15 carbon atoms; an aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 8 to 15 carbon atoms,R.sup.2 denotes an aliphatic hydrocarbon radical which has 10 to 35 carbon atoms and optionally contains double bonds,R.sup.3 denotes a hydrocarbon radical which is at least divalent and can also be heterocyclic, with inclusion of the ester oxygen or amide nitrogen from X, ##STR2## where R.dbd.H or C.sub.1 -C.sub.4 -alkyl, or R is a constituent of a cyclic structure,n denotes a number .gtoreq.2 and y denotes a number .gtoreq.

Abstract: A transversely or longitudinally heated atomizing furnace for flameless atomic absorption spectrometry. The atomizing furnace has a tube furnace segment and a specimen support disposed in the tube furnace segment. The specimen support is rigidly fixed in the tube furnace. For that purpose, the specimen support has on its underside a central peg or foot which is fixed in a complementary depression or recess formed centrally in the inner wall of the tube furnace, approximately opposite the sample insertion opening. The specimen support and the tube furnace segment are formed from electrographite. The gas-accessible surfaces of the specimen support and the tube furnace segment are coated with pyrocarbon. The two members are non-detachably connected to each other by means of the pyrocarbon coating. The specimen support extends over as large as possible a portion of the length of the tube furnace. On its upper side, the specimen support is formed with a trough that can receive up to 50 .mu.