. The Bell System technical journal . An outline of the methodfollows: Wood blocks of a convenient size are impregnated with thetoxic agent, usually in solution, and after evaporation of the solventthe blocks are placed in kolle flasks and supported on glass rods set inmalt-agar covered with the actively growing mycelia of the test conference advised the use of ConiophorQ cerehella as the test A LABORATORY EVALUATION OF WOOD PRESERVATIVES 197 fungus, but suggested that at least two species should be used in eachtest. After three or four months exposure to the wood-destroyingfungi, t
. The Bell System technical journal . An outline of the methodfollows: Wood blocks of a convenient size are impregnated with thetoxic agent, usually in solution, and after evaporation of the solventthe blocks are placed in kolle flasks and supported on glass rods set inmalt-agar covered with the actively growing mycelia of the test conference advised the use of ConiophorQ cerehella as the test A LABORATORY EVALUATION OF WOOD PRESERVATIVES 197 fungus, but suggested that at least two species should be used in eachtest. After three or four months exposure to the wood-destroyingfungi, the blocks are removed from the flasks, freed from adheringmycelium, and the weights taken before and after the test period usedas a measure of the amount of decay. The kolle flask method has much to recommend it, overcoming asit does many of the difficulties inherent in the petri dish , the test as standardized at Berlin presents serious kolle flasks are expensive, comparatively fragile, difficult to in. Fig. 2—Assay by kolle flask method. Porta incrassata used in comparison of southernpine heartwood versus sapwood. handle, inconvenient to store, and maintenance of proper moistureconditions is particularly difficult. For really satisfactory results theflasks during the tests should be kept at a constant humidity andtemperature. Despite all precautions there is the ever-present dangerof excess moisture and resultant lack of decay should the test blocktouch the agar or any condensed moisture on the flasks. Anotherunusual problem arose when certain over-ambitious fungi rotted thecotton plugs used to stopper the flasks and even continued to growinto other flasks where they did not belong. 198 BELL SYSTEM TECHNICAL JOURNAL A New Assay MethodBoth the petri dish and kolle flask methods had shown definitelimitations, and it became apparent that further experimentation on alaboratory assay-method should be directed along somewhat differentlines. By chanc
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
