Abstract: The invention relates to a connecting device for fluid circuits in column chromatography. To ensure an inert connection without dead volumes, the device comprises a glass or fused silica thick-wall body with an inner capillary channel connected to the outside through radial holes. In such holes, metal or fused silica capillaries are inserted and each fixed by means of a coupling carrying a capillary set screw and a coupling fixing screw, with said screws acting on opposite positions of said body wall.

Abstract: In the making of a mortar or concrete rich in aluminate cement wherein the cement is mixed with water to hydrate and is thereafter permitted to harden, the improvement which comprises adding to the mixture of cement and water an ionic compound containing anions X.sup.n- whereby there are formed mixed crystals of the formula[Ca.sub.2 Al(OH).sub.6 ].sup.- [( m/n)X.sup.n- (1-m) Al(OH).sub.4.sup.- mAl(OH).sub.3 ; aq].sup.-Preferably X is NO.sub.2.sup.-, SO.sub.3.sup.2-, S.sub.2 O.sub.3.sup.2-, Fe(CN).sub.6.sup.3-, PO.sub.4.sup.3-, FE(CN).sub.6.sup.4-, MnO.sub.4 --, ClO.sub.3.sup.- or CrO.sub.4.sup.2-. The mixed crystals are new.