There is disclosed a process for producing an olefin oxide, which is characterized by reacting an olefin with oxygen in the presence of a silver catalyst and 0. The method of the invention comprises the steps of sampling, eliminating impurities, separating, purifying, measuring the sum of Ar, collecting Ar, measuring the activity of 37Ar, etc. An opening having a width W2 is formed in the guide. The second protective casing has a hollow body for allowing the other cable to be disposed through. A removable divider connects to the storage basket, sectioning the basket into multiple storage compartments.