JOURNAL OF CHEMICAL EDUCATION
SOME ACCIDENTS IN JAPANESE SCHOOL LABORATORIES HIROMITSU SAWAMURA Hokkaido Gakugei University, Halrodate, Japan
GENERALLY speaking, accidents in chemical laboratories are not reported by school authorities. Hence the Ministry of Education of the Japanese Government does not have the total nnmber and data of such accidents. However, the following are accounts, with comments, of some accidents which were reported by the press. (1 ) August 15, 1944. The report says that during an experiment an assistant in the Department of Chemistry of Tokyo University died from an explosion. The explosion was probably caused by organic matter in a liquid air trap. Liquid nitrogen is preferable to liquid air as a cooling agent. (2) August 8, 1950. I n the Aomori-prefectural Hatchinoe high school more than ten students were injured in the arms by test tube explosions. Following instructions in their textbooks, they carried out an experiment to: "Ascertain the fact that oxygen is generated by the addition of concentrated sulfuric acid to potassium permanganate and heating." This explosion was probably caused by the formation of Mn20,, an unstable, dark brown, oily liquid. It decomposes explosively into MnOz and O2 a t about 70°C. Safety depends upon a suitable excess of H,S04, which dissolves Mnz07. The mixing ratio of 0.2 g. of KMnOr, to 3-3.5 g. of concentrated HzSOais suitable for highschool students. This case shows a lack of knowledge and caution, and, moreover, a lack of preliminary experiment. (3) June 27, 1952. In the primary school in Niigata an explosion occurred when the teacher ground a mixture of red phosphorus and glass powder, in order to make a match box. Forty-three people were injured. It was reported that the explosion was caused by
KC10, which had been left in the mortar. The teacher had used the same mortar in the previous lesson to make a match head by mixing MnO,, S, and KC103. The heat of friction caused the red phosporus to ignite explosively with the oxygen of the potassium chlorate. This case shows extreme carelessness. Also, large amounts of chemicals were probably used. It is essential to remember that only small quantities of hazardous chemicals should he used. A few likely sources of accidents are as follows: A Detonating Gas. Many accidents are caused in primary and junior high schools by explosions of detonating gas. Care must be talcen when hydrogen or a mixture of hydrogen and oxygen is ignited. Kipp Generator. Hydrogen sulfide is usually generated in a Kipp's apparatus. When a Kipp generator is filled with sticks of FeS, one must be careful not to fill the lower compartment, or to use small sticks or dust of FeS. Poison of Hydrogen Sulfide. Hydrogen sulfide is a common reagent in chemical laboratories. Its toxicity is apt to be forgotten. The author was reminded of it when a cat was an accidental victim! Ammonia. I n the summer re-education course for junior high-school teachers, a teacher opened a bottle of ammonium hydroxide (28 percent solution), the contents of the bottle burst out, and four teachers were drenched. When a bottle of ammonium hydroxide is opened in warm weather, care must be taken. Fires. After the war several schools in Japan were burnt down from various causes: (a) ignition of soybean oil, ( b ) defective electric heaters, (c) leakage of water onto metallic sodium, (d) electrical ignition of oil on the floor of a generator room.
