Crucibles wetting

Boron nitride is one of the most outstanding corrosion-resistant materials. It is inert to gasoline, benzene, alcohol, acetone, chlorinated hydrocarbons and other organic solvents. It is not wetted by molten aluminum, copper, cadmium, iron, antimony, bismuth, silicon, germanium, nor by many molten salts and glasses. It is used extensively as crucible material, particularly for molten metals, glasses and ceramic processing. 

A wet-ashing procedure for analysis of fatty animal tissue was modified by using Teflon-lined bombs rated for use at 340 bar instead of open crucibles. Bombs cooled to well below 0°C were charged with fuming nitric and fuming sulfuric acids (1 ml of each) and adipose tissue (0.5 g), removed from the cooling bath and sealed. After 10 min delay, the bombs exploded, probably owing to development of... 

Remove the filter paper and precipitate from the funnel and carefully fold and place into the preweighed crucible. If you find the precipitate to be quite bulky and difficult to handle, place the folded filter paper head first into the crucible, so that if any precipitate oozes out, it will go into the crucible. Be careful not to tear the filter paper at this point. It is wet and quite fragile. You will need at least 60 min to finish the experiment. If you do not have this amount of time, store the crucibles outside of your desiccator until the next laboratory period. 

On February 24, 1829, Berzelius wrote to Eilhard Mitscherlich, "Wollaston s death grieves me. His specifications for making platina pliable were circulated at the same time as the news of his death. As I got iridium to cohere in an analogous manner, I was struck all the more by his simple method, went out into the laboratory, where I had a wet filter with platina on it, partly washed, which I pressed in a vice, dried, and ignited over a spirit lamp in a small platina crucible, and got it so coherent that it could no longer be broken with the fingers and could easily be cold-hammered. That s as far as I have yet gone. That was ten minutes work, then I had to let it wait for a better time (83). 

Weigh 0.5 g of finely crystalline potassium chlorate and mix it with an equal amount of powdered sugar, using a rod (be careful ). Pour out the mixture onto the lid of a crucible and wet it with two or three drops of concentrated sulphuric acid. What occurs What properties of potassium chlorate do the above experiments indicate ... 

Put several iron II) sulphate crystals on the lid of a porcelain crucible, heat them, and then strongly roast them. Hold litmus paper wetted with water over the crystals. What happens Write the equation of the reaction. 

Army). Mix the original wet sample and transfer ca 10 g portion to a tared Gooch or Selas No 2001 crucible. Wash with five 20 ml portions of cold (0 to 15°) distd w, which has been boiled and cooled prior to the test. Allow each portion of w to remain in contact with LA for 3 mins. Add to the filtrate 5 drops of 0.1% methyl orange indicator and note if the sample is free from acidity as shown hy the absence of a red tinge... 

Fill a small iron crucible about one-half to two-thirds full of magnesium powder. Bore a pinhole in the iron lid and then place the lid on the crucible. Lute the lid to the crucible with wet asbestos pulp and close the hole with the same material. (If a lid is not available, twist the crucible on a piece of asbestos board like a biscuit cutter until a deep groove has been cut in it and then lute it to the crucible as before.) Dry the crucible and its contents in an air oven or on the hot plate and when they are dry pierce a small hole in the asbestos plug with a pin. Place the crucible in a circular hole... 

The first condition specifies the joining of the meniscus and the crystal, and the second condition specifies the wetting at the crucible wall. The radius of the crystal at the trijunction R(f, t) is left undetermined and must be set by an auxiliary constraint, such as the wetting angle there. 

Place a few small lumps of marble (calcium carbonate) in a small porcelain crucible. Cover the crucible in order to keep in the heat, and heat it strongly for 20 minutes with a Bunsen flame. When the product has cooled, wet each lump with a single drop or two of water and wait a few minutes, if necessary, to observe the effect. The lumps should grow very hot, and steam be driven off. Then wet the product with somewhat more water, and test the reaction of the moist mass towards litmus. The litmus is colored strongly blue by the suspension. 

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