INFOTRONICS CORP

for which they were designed, are capable of an ... that have received the greatest at- tention in attempts to ... firing to obtain a material of high...
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for which they were designed, are capable of an amazingly high degree of precision and accuracy. I t is the remaining two phases t h a t have received the greatest attention in attempts to improve the determination. One of the early attempts to improve the combustion phase was the introduction of the " e m p t y t u b e " method by Belcher and Spooner (#) in 1943, and the subsequent improvement of the method by Belcher and I n g r a m (1). These methods involve the slow vaporization of the sample into a quartz tube maintained at a high temperature and devoid of filling or catalysts, turbulence being obtained by the internal use of baffles. This method has enjoyed popularity in E n g l a n d b u t has never been widely accepted in the United States. An interesting development in combustion tube filings is the use of various metallic oxides other t h a n t h a t of copper as catalysts for the decomposition of organic m a t e rials to carbon dioxide and water. T h e decomposition product of silver p e r m a n g a n a t e as described by Korbl (7) has proven to be of value by m a n y workers. T h e catalyst is a microporous matrix of manganese dioxide in which very fine particles of metallic silver are dispersed. T h e advantages claimed are low operating temperature, high capacity, rapidity of oxygen flow, and the ability to scavenge large amounts of the halogens and sulfur. I t is the last property t h a t perhaps removes the material from the classification of a catalyst because it will be exhausted by continued dosage with the halogens and sulfur. Another oxide catalyst which is becoming very popular is the mixed oxide of cobalt, cobalto-cobaltic oxide. I n the preparation of this material as described by Vecera (18) and his co-workers, it is advocated t h a t the cobaltic oxide be supported on fired asbestos fibers. Macdonald (9) suggests mixing the cobaltic oxide with starch before firing to obtain a material of high porosity and good mechanical strength. Low operating temperature and an extremely high activity are characteristics of this catalyst. An entirely noveï t y p e of sample

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INFOTRONICSC O R P . 1401 SOUTH POST OAK ROAD / HOUSTON, TEXAS 77027 Circle No. 216 on Readers' Service Card

VOL.

36, NO. 7, JUNE 1964

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33 A