Abstract: In an apparatus for closing a fireproof door in case of emergency, the fireproof door and a release, which is secured to a door frame, are interconnected by a link mechanism comprising first, second and supplemental link arms. One end of the first link arms is pivoted to a driving shaft of a door closer secured to the fireproof door. The other end of the first link arm is pivoted to one end of the second link arm, the other end of which is pivoted to the release. The supplemental link arm is connected between the central point of the second link arm and a slider which is slidably mounted inside the release and latched by a latch mechanism when the fireproof door is open.When the slider is released from the latch mechanism by electrizing a solenoid which operates the latch mechanism, the slider is slid inside the release by the closing force of the door closer transmitted via the link mechanism, thereby closing the fireproof door.

Abstract: A foam type fire extinguishing agent for hydrophilic combustible liquids which comprises(a) a hydroxycarboxylic acid or salt thereof represented by one of the following general formulae and/or a lactone formed in equilibrium with the corresponding hydroxycarboxylic acid:HO--HCOH).sub.n COOX (Ia)H--HCOH).sub.n COOX (Ib)CH.sub.3 (CH.sub.2).sub.m (HCOH).sub.n COOX (Ic)H--HCOH).sub.n (CH.sub.2).sub.