Abstract: A copolyester film is disclosed which comprises a copolyester in which the dicarboxylic acid component comprises 100 to 85 mole percent of terephthalic acid and the diol component comprises 65 to 97 mole percent of 1,4-butanediol and 3 to 35 mole percent of a polyethylene glycol with a molecular weight of 106 to 550. The copolyester has a reduced viscosity in the range of 0.8 to 1.4 dl/g as measured at a concentration of 0.5 g/dl in a 1:1 (by weight) solvent mixture of phenol and tetrachloroethane at 30.degree. C. The copolyester has a main endothermic peak with a peak maximum temperature of 160.degree. C. to 200.degree. C. and at least one subsidiary endothermic peak with a peak maximum temperature of 30.degree. C. to 80.degree. C. in differential scanning calorimetry with the ratio (R) of the area occupying not less than 40.degree. C. in the subsidiary endothermic peak, the main endothermic peak area being within the range of 3 percent to 20 percent.

Abstract: An apparatus for measuring the quantities of chemical substances contained in a solution to be assayed by using a chemical-substance sensitive sensor consists of a potentiometric electrode which responds selectively to chemical substances, and a liquid-junction type reference electrode including a tube, a porous thread member housed in the front end opening of the tube and having a pore capacity of 0.2 cc/g or more and at least the surface of which is hydrophilic, a silver-silver chloride wire is provided and housed in the tube so that at one end of the wire is in contact with the thread member and the wire which extends along the tube. The wire is connected to a connector at the other end opening of the tube, an electrical insulating resin fills said tube, at least at the front end portion thereof, for fixing both the silver-silver chloride wire and the thread member by contact therewith and for stopping said tube. An internal solution is retained by suction in said porous thread member.

Abstract: An apparatus for filtering a suspension by at least one aggregate of membranes made of a high molecular weight compound porous hollow fibers to separate a filtrate from the suspended matter contained in the suspension, backwashing the aggregate of membranes with a backwashing gas to clean it and minimizing the amount of suspended matter entrained by the backwashing gas, and repeating the filtration and backwashing alternately, comprises a filtering vessel divided into a feed region and a filtrate region, the filtrate region being above the feed region, an inlet for the suspension at the feed region, an outlet for the filtrate at the filtrate region, an inlet for a backwashing gas in the filtrate region, an outlet for the backwashing gas in the feed region, a partition plate in the filtering vessel to support the aggregate of membrane filters and to divide the inteior of the filtering vessel into the filtrate region and the feed region, an outlet for a portion of the suspension in the feed region at a position