Abstract: A magneto casing for an engine connected to an engine crankcase in liquidtight sealing relationship by means of an oil seal which permits small amounts of air to pass therethrough is formed therein with an air passage having mounted therein a filter which is repellent to water but permeable to air. When the internal pressure of the magneto casing undergoes changes due to variations in the pressure within the crankcase which occurs when the engine operates, only air is allowed to flow into and out of the magneto casing through the filter in the air passage and water is prevented from entering the magneto casing.

Abstract: In the process for preparing tetrahydrofuran by the dehydrocyclization of 1,4-butanediol in the presence of a non-volatile acid catalyst, wherein vapor mixture of water and tetrahydrofuran is continuously taken out from the reaction zone and subjected to the azeotropic distillation in three distillation columns operated under specified conditions thereby obtaining tetrahydrofuran of high quality in a high yield.

Abstract: Butanediol and/or butenediol are prepared by hydrolyzing diacetoxybutane and/or diacetoxybutene in the presence of a cation-exchange resin and recovered by fractional distillation. By the treatment of the hydrolyzed product with an anion exchange resin at any stage before the butanediol and/or butenediol are fractionated, butanediol and/or butenediol are recovered in high yield.

Abstract: A fractional distillation method of separating diacetoxybutene isomers from a reaction mixture produced from the reaction of butadiene, acetic acid and molecular oxygen comprises employing a series of at least two distillation towers, one of said towers being used for distillation of water and acetic acid under a pressure of 30 - 250 Torr and a tower bottom temperature of 190.degree. - 120.degree. C and the other being used for separation of high boiling point materials under a pressure of 2 - 100 Torr and a tower bottom temperature of 190.degree. - 120.degree. C, the temperature of all tower bottoms being from 190.degree. - 120.degree. C.