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Seite 48 - The crucible should be supported on a platinum triangle with the bottom from 6 to 8 cm. above the top of the burner. The flame should be fully 20 cm. high when burning free, and the determination should be made in a place free from draughts. The upper surface of the cover should burn clear, but the under surface should remain covered with carbon. To find Volatile Combustible Matter, subtract the per cent.
Seite 428 - A large excess of silica indicates a sa.ndy clay, and if much is present in the analysis of a fire clay, it indicates low refractoriness. 6. The quantity of organic matter. If this is determined separately, and it is present to the extent of several per cent, it would require slow burning if the clay was dense. 7. The presence of several per cent. of both lime (CaO) and carbon dioxide (CO2) in the clay indicates that it is quite calcareous.
Seite 421 - The term clay is applied to a natural substance or rock which, when finely ground and mixed with water, forms a pasty, moldable mass that preserves its shape when air-dried and when burned, changes to a hard, rock-like substance by the coalescence of its particles through softening under the action of heat.
Seite 63 - It might perhaps be said that the more lignitic the character of the coal, the greater the possibility of its including a large percentage of water, but in general the percentage varies with the exposure of the coal, the season of the year, and the state of the weather. It...
Seite 50 - The difference in results obtained by three, four, and five minutes' preliminary treatment is small and in all subsequent experimental tests the time of the preliminary heating was four minutes." The experiments which follow will show that with some Philippine coals a longer period of preliminary treatment is necessary to give very accurate results.
Seite 167 - The direct petrographical suggestion is that they are chemical precipitates. If now we accept this hypothesis, it becomes apparent that there are three possible sources for the silica so precipitated, viz.: (1) Siliceous springs in the bottom of the ocean, similar to those well known in volcanic regions; (2) radiolarian and other siliceous remains, which may have become entirely dissolved in sea water; and (3) volcanic ejectmenta, which may have become similarly dissolved.
Seite 52 - ... determination of magnesia, as large variations could be obtained by exposing the crystalized double phosphate to varied conditions ; and yet this determination, properly executed, is one of the most accurate known in analysis. It is easily seen that the following elements will modify the result of the amount of volatile matter driven off from a sample of coal contained in a covered platinum crucible : weight of coal and of crucible; degree and duration of heat; condition of coal. I hope to show...
Seite 403 - Cebú, and in the Compostela-Danao district the natives have more or less familiarity with underground work, gained by experience of a score of years under the tutelage of the Spaniards. The present wage in this field is 40 centavos and subsistence, for the outside laborers, and 50 centavos for the underground man; however, of late the Insular Coal Company lias found it best to pay so much a foot for driving a drift.
Seite 48 - Place 1 gram of fresh, undried, powdered coal in a platinum crucible weighing 20 to 30 grams and having a tightly fitting cover. Heat over the full flame of a Bunsen burner for seven minutes. The crucible should be supported on a platinum triangle with the bottom 6 to 8 centimeters above the top of the burner.