Meker

Flame Sources Atomization and excitation in flame atomic emission is accomplished using the same nebulization and spray chamber assembly used in atomic absorption (see Figure 10.38). The burner head consists of single or multiple slots or a Meker-style burner. Older atomic emission instruments often used a total consumption burner in which the sample is drawn through a capillary tube and injected directly into the flame. 

The contents of the flask while still hot are poured into a 30-cm. evaporating dish and the alcohol is evaporated on a steam bath. The dry salt is pulverized and thoroughly mixed with 390 g. of calcium oxide, placed in a 2-I. copper retort (Note 3), and heated with the full flame of a Meker burner. The distillate is placed in a distilling flask and heated on a steam bath all material distilling under 90 is removed and discarded. The residue is then allowed to stand over solid potassium hydroxide for twelve hours and is finally fractionated. The dimethyl-pyridine distils at i42-i44°/743 mm. The yield is 35-36 g. or 62-64 per cent of the theoretical amount based on the 3,5-dicarb-ethoxy-2,6-dimethylpyridine, or 30-36 per cent based on the original ethyl acetoacetate. 

Mekerbrenner, m. Meker burner. Mekoninsaure, /. meconinic acid. 

The flask is then fitted with a separatory funnel and a condenser for distillation, and heated with a Meker burner to steam distil the bromoform and carbon tetrabromide (Notes 2 and 3). 

No. 41 or 541 filter paper. Wash the precipitate first with warm, dilute hydrochloric acid (approx. 0.5M), and then with hot water until free from chlorides. Pour the filtrate and washings into the original dish, evaporate to dryness on the steam bath, and heat in an air oven at 100-110 °C for 1 hour. Moisten the residue with 5 mL concentrated hydrochloric acid, add 75 mL water, warm to extract soluble salts, and filter through a fresh, but smaller, filter paper. Wash with warm dilute hydrochloric acid (approx. 0.1M), and finally with a little hot water. Fold up the moist filters, and place them in a weighed platinum crucible. Dry the paper with a small flame, char the paper, and burn off the carbon over a low flame take care that none of the fine powder is blown away. When all the carbon has been oxidised, cover the crucible, and heat for an hour at the full temperature of a Meker-type burner in order to complete the dehydration. Allow to cool in a desiccator, and weigh. Repeat the ignition, etc., until the weight is constant. 

To determine the exact Si02 content of the residue, moisten it with 1 mL water, add two or three drops of concentrated sulphuric acid and about 5 mL of the purest available hydrofluoric acid. (CARE ) Place the crucible in an air bath (Section 3.21) and evaporate the hydrofluoric acid in a fume cupboard (hood) with a small flame until the acid is completely expelled the liquid should not be boiled. (The crucible may also be directly heated with a small non-luminous flame.) Then increase the heat to volatilise the sulphuric acid, and finally heat with a Meker-type burner for 15 minutes. Allow to cool in a desiccator and weigh. Re-heat to constant weight. The loss in weight represents the weight of the silica (Note 2). 

For flame emission measurements, burners of the Meker type with a circular orifice covered by a grille are used whereas in atomic absorption spectrometry, a slit burner is preferred. In both cases, the flame consists of two principal zones or cones (Figure 8.21(b)). The inner cone or primary... 

Now Bunsen burners are not the only kind. There are Tirrill burners and Meker burners as well. Some are more fancy than others, but they work pretty much the same. So when I say burner anywhere in the text it could be any of them. 

In any case, the sample is usually contained in a crucible (prepared in advance by ignition without a sample) and placed in the oven or over the Meker burner for a specified period of time or to a constant weight, as in the loss on drying. The calculation is also similar to loss on drying, and the weight of the crucible will need to be subtracted if the tare feature of a balance is not used. 

To disintegrate the filter paper, the rinsed filter paper containing the precipitate is folded and placed into a preweighed porcelain crucible and the crucible is heated, first cautiously with a cooler Bunsen burner flame, so as to dry and char the filter paper, and then with the full heat of a Meker burner. For this final ignition step, the crucible should be tilted to one side and partially covered with the crucible lid so that the burner flame can be directed to the bottom of the crucible, thus avoiding engulfing the... 

Finish the experiment as directed in Experiment 6, steps 13 and 14. Slowly dry the filter paper using a Bunsen burner. Heat until black. Then incline the crucible at an angle, Hd ajar, and direct the flame of a Meker burner to the bottom of the crucible, allowing air to get inside the crucible (Figure 3.9). Apply the full heat of the Meker burner for 20 min, or if only one Meker burner is available, alternate, as before, with a Bunsen burner for V2 h. Cool and weigh. Calculate the percent Fe in the sample. The precipitate is Fe203. 

Meker burner support stand triangle crucible support... 

Heat the crucible and lid with the Meker burner repeatedly until constant weight is achieved. 

Considerable time is saved by using a Meker or triple burner for raising the apparatus to reaction temperature, but an ordinary Tirrill burner is sufficient for the reaction. 

Many early experiments were carried out with the Meker type of burner. A perforated metal plate is placed on top of an open pipe (the thicker the plate, the more stable is the flame). On ignition, a number of small cones... 

For analyses, an 0.5 g sample is weighed into a porcelain boat and inserted into the combustion tube with an oxygen flow of —30 cc/min. With a cold trap in place, the sample is ignited by heating the combustion tube with a meker burner. The coal sample is allowed to burn freely, and then the temperature is raised to the burner maximum for 5 min. The combustion tube is cooled for 5 min and separated from the condenser section. The condenser is removed from the cold trap and allowed to warm to ambient temperature. Add 10 ml of water to the condenser and flush into a 50 ml volumetric flask. Make to volume with water and mix. Take an aliquot of 15 ml or less containing up to 0.3 fxg of selenium and proceed as in the hydride method for arsenic, tin, and bismuth by AAS, as previously described. 

An Intimate mixture of 25g stibnite, llg iron powder or filings, 2.5g anhydrous sodium sulfate, and 0.6g charcoal is placed in a covered crucible and heated about 20 minutes with a Meker burner so that the fusion mixture softens but does not quite melt This is determined by momentarily stirring with an iron rod. The melt is allowed to cool and the crucible is broken. A mass of crude fused antimony weighing about 15g is found at the bottom this is mechanically cleaned and then washed with hot water. 

Twenty-five grains of litharge are mixed well with 1.5g of very due charcoal and heated over a Meker burner in a large covered crucible for about one-half hour. The molten lead is poured into a dean iron dish and allowed to cool. Yield about 20g. 

Twenty grains of finely powdered native stannic oxide and an equal weight of potassium cyanide (mixed in a mortar) are heated in a crucible over a Meker burner for about one-half hour. 

The product is ground with XOg of ammonium chloride in a mortar and this mixture is heated in a nickel crucible for one-half hour over the full dame of a Meker burner. The product is cooled and pulverized and extracted three times with IN hydrochloric acid. The residue is boiled with 100ml of distilled water, filtered, and the white powder dried at 100°C. 

Ten grams of finely powdered boric oxide are intimately ground with 20g of urea and heated in a covered nickel crucible for about SO minutes over a Meker burner with slowly rising temperature to a bright red heat. The cooled mass is treated as in (I). 

Thirty-six grams of powdered stibnite (SbaS8) are ground thoroughly in a mortar with 43g of anhydrous sodium sulfate and 16g of charcoal. The mixture is placed in a large clay crucible (the latter should be about half-filled), covered with a thin layer (about % inch) of charcoal and heated over a Meker burner to a state of quiet fusion, then ten minutes longer. The melt is poured into an iron dish, allowed to cool and then powdered. The material is then boiled under reflux with 7g of sulfur powder in 300ml of water, suction-filtered, and the product is isolated as described in (I). 

Two hundred grams of citric acid (0.95 mole) (Note 2) is placed in the reaction flask (Note 3) and heated with a free flame until melted. Then the flask is heated very rapidly with a large Meker burner, and the distillation is completed as rapidly as possible (ten to twelve minutes). Care must be taken to avoid superheating (Note 4). The distillate consists of water and itaconic anhydride, most of which distils at 175-190°. The distillate is immediately (Note 5) poured into a separatory... 

A rapid, alternative method of crystal separation is the addition of solid potassium chloride (an amount necessary to fill the crucible) directly into the untreated, fused mass (obtained after cooling to room temperature), followed by heating the new mixture to its fusion point by means of a Meker burner in a fume hood and maintaining this temperature for 1 or 2 hours. The molten potassium chloride will rapidly dissolve the magnesium fluoride and decompose the tungstate. The crucible is allowed to cool, and the fused mass is treated as described in the previous section. However, dissolving of the flux will now be much more rapid. 

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