Abstract: A pellet of potassium superoxide, as the oxygen-yielding chemical, with an additive of catalyst material for stimulating the release of oxygen is improved by providing a concentrated addition of the catalyst material on the surface of the pellet; this permits a uniform release of oxygen during the entire period of the use of the pellet. With the pellet, oxygen is split off as required at the very outset of breathing with the breathing apparatus and a release of oxygen in excess of demand as use continues is avoided. A pellet of this type includes a compressed core body containing substantially potassium superoxide and surrounded by a compressed jacket made of highly catalyzed potassium superoxide material.

Abstract: Organic isocyanates are detected with an indicator comprising bis-4-(dimethylamino)-phenyl-methylenimine-hydrochloride provided on a carrier along with a catalyst for its reaction with the organic isocyanates contained in a tested gas. Through an acid developer brought subsequently into contact with the indicator, this reaction occurs and thus the concentration of the organic isocyanates is made evident by a red coloration of the indicator.

Abstract: An indicator for determining sulfur dioxide is required for monitoring, e.g. the content of the noxious substance in the air, due to emissions or in particularly jeopardized working places. With a high sensitivity and spacificity, it must allow simple handling and be ready to use immediately even after prolonged storage. Suitable for this purpose is the color reaction of nitroprussiate, which only takes place in the moist state. In order to attain a sufficient sensitivity an additive is principally required. Usual additives, however, lead on storage in the moist state to rapid decomposition so that immediate use is not possible after prolonged storage. This can be remedied by the use of a tetra-substituted ammonium salt as an additive, which yields at the same time a good sensitivity and storability in the moist state for months. It is preferably used in the form of the known test papers of test tapes.

Abstract: A gas monitor for measuring a test gas equipped with an indicator band comprises a foretube for chemically converting a gas to be measured contained in the test gas, the foretube comprising a glass tube having a tip at each end to be broken away for the passage of the gas therethrough and including a conversion effecting filling in the glass tube and a capillary tube defining a conduit parallel to the filling. In a gas monitor, an indicator band impregnated with an agent reacting with the special gas to be measured and contained in the tested gas, is moved to be exposed to a gas sample. For some gases, for example vinyl chloride, no chemically reacting indicators are known. In such instances, the sample to be tested is first directed through a foretube where the gas to be measured is converted to obtain a gas reacting with the indicator and thus measurable. In the inventive foretube, aside from the filling effecting the conversion, a capillary tube is mounted forming a parallel conduit.