. Bulletin of the Department of Agriculture. Agriculture; Agriculture. EXAMINATION OF BITUMINOUS ROAD MATERIALS. 31 1899, volume 21, page 1116. One grain of the material is placed in a platinum crucible weighing from 20 to 30 grams and having a tightly fitting cover. It is then heated for seven minutes over the full flame of a Bunsen burner, as shown in figure 15. The crucible should be supported on a platinum triangle with the bottom from 6 to 8 centimeters above the top of the burner. The flame should be fully 20 centimeters high when burning freely, and the determi- nation should be ma
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. EXAMINATION OF BITUMINOUS ROAD MATERIALS. 31 1899, volume 21, page 1116. One grain of the material is placed in a platinum crucible weighing from 20 to 30 grams and having a tightly fitting cover. It is then heated for seven minutes over the full flame of a Bunsen burner, as shown in figure 15. The crucible should be supported on a platinum triangle with the bottom from 6 to 8 centimeters above the top of the burner. The flame should be fully 20 centimeters high when burning freely, and the determi- nation should be made in a place free from drafts. The upper sur- face of the cover should burn clear, but the under surface should remain covered with carbon, excepting in the case of some of the more fluid bitumens, when the under surface of the cover may be quite clean. The crucible is removed to a desiccator and when cool, is weighed, after which the cover is removed, and the crucible is placed in an inclined position over the Bunsen burner and ignited until nothing but ash remains. Any carbon deposited on the cover is also burned off. The weight of ash remaining is deducted from the weight of the residue after the first ignition of the sample. This gives the weight of the so-called fixed or residual carbon, which is calculated on -a basis of the total weight of the sample, exclusive of mineral matter. If the presence of a carbonate mineral is suspected, the per- centage of mineral matter may be most accurately obtained by treating the ash with a few drops of ammonimn carbonate solution, drying at 100° C, then heating for a few minutes at a dull red heat, cooling and weighing. An excellent form of crucible for this test is shown in figure 15. It has a cover with a flange 4 millimeters wido, fitting tightly over the outside of the crucible, and weighs complete about 25 grams. Owing to Budder expansion in burning some of the more fluid bitu- mens, it is well to hold the rover down with, the en
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