A Manual of Quantitative Chemical Analysis for the Use of Students

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H. Holt, 1880 - 279 páginas
 

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Página 44 - In the course of a longer or shorter space of time, the mass will slake and crumble after the manner of lime ; still better, this may be hastened by bringing the contents of the capsule to the boiling-point, either over a lamp or water-bath. At the same time, water is put into the crucible, to...
Página 97 - ... all the particles of carbon may be observed. The operation should always be conducted under the same circumstances as to heat and length of time. The evolution of gas having ceased (in operating upon steel the reaction must continue two to three hours), place the tube in a large vase filled with water to bring the solution always to the same temperature. This precaution is indispensable because the same liquid is darker when warm than when cold. Afterward, pour off as exactly as possible the...
Página 43 - The former amount is most commonly used, it being sufficient and best manipulated in the crucible; a gramme, however, may be conveniently employed. The weighed mineral is placed in a large agate mortar, or better in a glazed porcelain mortar, of half to one pint capacity. An equal quantity of the granular...
Página 64 - When the iron is quite dissolved, 30 grs. of the finely pounded and dried sample of manganese ore to be tested are put into the flask, the cork replaced, and the contents again made to boil gently over a gas flame until it is seen that the whole of the black part of the manganese is dissolved. The water in the small flask or beaker is then allowed to recede through the bent tube into the larger flask, more distilled water is added to rinse out the small flask or beaker and bent tube, the cork well...
Página 59 - C.) directly with strong solution of sodium carbonate in a platinum dish as above, filter and wash thoroughly with hot water. Acidify the filtrate with hydrochloric acid, evaporate to dryness, and determine the silica as usual. It represents (B) or the hydrated silicic acid. Add together the weights of (B) and (C), thus found, and subtract the sum from the weight of the first residue (A + B + C). The difference will be the weight of (A) or the silica in combination with the bases of the clay. If...
Página 46 - ... capacity, and during the evaporation is never filled to more than two-thirds its capacity. After the filtrate has been evaporated to dryness, the bottom of the dish is dried, and on a proper support heated very gently by a Bunsen flame, to drive off the little sal-ammoniac. It is well to cover the capsule with a piece of thin platinum to prevent any possible loss by the spirting of the salt ; after the sal-ammoniac has been driven off by gradually increasing the heat, the temperature of the dish...
Página 44 - The crucible is now allowed to cool, when the contents will be found to be more or less agglomerated in the form of a semifused mass. A glass rod or blunt steel point will most commonly detach the mass, which is...
Página 101 - ... undissolved. The insoluble silica and graphite are thrown on a filter (which has been dried at 100° C. and carefully weighed), washed with cold water until the washings give no reaction for iron when tested with potassium ferrocyanide, then washed with boiling water containing 5 per cent of nitric acid. The silica and graphite are then dried on the filter at 100° C., and weighed, ignited in a porcelain crucible, and the weight carefully taken.
Página 64 - ... is then allowed to recede through the bent tube into the larger flask, more distilled water is added to rinse out the small flask or beaker and bent tube, the cork well rinsed, and the contents of the flask made up to about 8 or 10 ounces with distilled water.
Página 46 - Bunsen flame to drive off the little sal-ammoniac. It is well to cover the capsule with a piece of thin platinum to prevent any possible loss by the spitting of the salt after the sal-ammoniac has been driven off. Gradually increasing the heat, the temperature of the dish is brought up to a point a little below redness, the cover being off (the cover can be cleansed from any sal-ammoniac that may have condensed by heating it over the lamp). The capsule is again covered, and when sufficiently cooled,...

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