Abstract: Hydrophilic colloids, such as gelatin, which are employed in the manufacture of photographic elements are commonly treated with a hardening composition, among the most useful of which are hardening compositions containing vinyl sulfone hardening agents such as bis(vinylsulfonyl)methane. In accordance with this invention, a sulfate, such as sodium sulfate, is utilized as both an effective conductivity marker and an effective inhibitor of homopolymerization in such hardening compositions.

Abstract: A mine prop provided with an overpressure valve of large flow-through section which opens when excessive forces suddenly act on the prop to discharge pressure fluid from the interior of the prop. The overpressure valve comprises a hollow cylindrical housing forming at one end a valve seat communicating with the fluid-filled inner space of the prop and a valve member axially guided in the housing for movement between a closed position engaging the valve seat and an open position. The fluid-filled space of the prop communicates with channels leading to the outside of the prop. The valve member is normally maintained in the closed position by a gas pillow under high pretension confined in a pressure space delimited peripherally by the wall of the valve housing and at opposite ends respectively by the valve member and a plug fluid tightly mounted in and closing the other end of the housing.

Abstract: A walking mine support includes a roadway support unit and a face-gallery support unit laterally of the same. The two units are linked by one or more four-pivot couplings whose members can tilt both lengthwise and transversely of the elongation of the roadway and permit walking movements of the units with reference to one another without interfering with proper support of either the roadway or the face-gallery.

Abstract: A walking mine support unit has a pair of adjacent supporting frames each having a multi-partite sole plate and a multi-partite roof shield. The sole plate and roof shield of each frame are connected only at their respective leading and trailing ends, by hydraulic rams which permit the roof shields to be raised and lowered relative to the sole plates, and by four-bar linkages which permit length-wise displacement of the roof shields parallel and relative to the sole plates. A multi-section overshield is located above each of the roof shields and connected thereto by adjustable supports. An arrangement is provided for advancing the unit in stepwise manner.

Abstract: In a longwall mining operation the roof of the breast extending laterally from a heading or gangway is supported by at least two pairs of pit props. Each pair is substantially identical, having an elongated upper part and an elongated lower part displaceable away from each other by hydraulic rams. In addition a shield is provided extending vertically between the upper and lower parts of each prop at the upstream end of the prop turned toward the stowage area. In addition the props furthest from the mine are substantially longer than the props closest to the mine and are provided at their ends turned toward the stowage area with side shields forming a closed chamber so as carefully to segregate the gob from the breast. The upper parts of the props are formed of several articulated sections so as to allow these upper parts to conform to the shape of the roof.

Abstract: In longwall mining wherein a mine roof is normally supported by a succession of arches each in turn supported at one mine wall on a respective leg, a plurality of vertically expensible holders are pressed up against a plurality of respective adjacent arches with a common first beam, and legs of the thus-supported arches are removed so that the mine wall can be worked at this location. For advancing along the longwall all of the holders except the holder at one end of the row of holders are pressed upwardly against the respective arches with a second beam. The leg of the arch of the end holder is replaced and then the first beam is dropped down away from the row of holders. The end holder is then displaced to the opposite end of the row and the first beam is advanced toward this other end and the end holder is positioned under the arch immediately adjacent the other end.

Abstract: Stable nitroxyl radicals are useful as oxidants in photographic elements or film units.

Abstract: A method for advancing and supporting an underground mine gallery in which a groove following the outline of the cross-section of the mine gallery is formed in the mine face and simultaneously thereto a plurality of bore holes are drilled in the part of the mine face located inwardly of the groove, in which a support frame is then placed into the groove and braced against the surrounding rock, whereafter explosives placed in the bore holes are exploded to remove the part inwardly of the groove from the mine face, while the loose material formed during the preceding steps is transported away from the mine face; and a machine for carrying out the method which is advanced after the above-mentioned steps are performed, whereafter the above-mentioned steps are repeated to thus advance the underground mine gallery while properly supporting the same during such advance.

Abstract: A pit prop assembly for use in a mine having a floor, a roof, and a face, comprises a pair of pit props having parallel elongated floor-engaging bases on each of which is pivoted a roof-engaging arm which may be pressed against the roof by means of a hydraulic ram extending vertically between each base and the respective arm. A pair of telescoping elements extend longitudinally between these two bases and one of the elements is pivoted at its front and rear end on respective front and rear end of one of the bases and the other element pivoted at its front and rear end on the respective front and rear end of the other base. A longitudinal-displacement ram is provided between these telescoping elements so that the two pit props can be displaced longitudinally relative to each other. In addition a transverse ram forms the connection between the rear of one of the elements and the corresponding rear of the corresponding base so that transverse displacement or swiveling of the two pit props is also possible.