Powder running

Sometimes, in addition to the igniter bag, a charge of Black Powder running through the propellant in the form of a core is also used Refs 1) Hayes (1938), pp 34-35 2) Ohart (1946), pp 184 189 3) Also see Sect 3, Part D of Vol 4, pp D795-97... 

Mg2+ influences calcite dissolution rates the same way, but not to the same extent as Ca2+. The inhibition effects of Mg2+ can be described in terms of a Langmuir adsorption isotherm. Sjoberg (1978) found he could model results for the combined influences of Ca2+ and Mg2+ in terms of site competition consistent with ion exchange equilibrium. The inhibition effects of Mg2+ in calcite powder runs increase with increasing Mg2+ concentration and as equilibrium is approached. 

Available forms (1) Chromium metal as lumps, granules, or powder (2) high- or low-carbon ferro-chromium (3) single crystals, high-purity crystals, or powder run 99.97% pure. 

Further experimentation showed that no complex formed when dispersed sodium was added to dimethoxyethane that had been carefully dried and purified by distillation from a sodium-naphthalene addition compound, yet ferric chloride was reduced almost as readily as when the so-called complex had been preformed (12). This was taken as evidence that the ether was acting also as a solvent for the ferric chloride and that the complex must have been dependent on impurities in the commercial-grade ether, which either reacted with sodium or acted as a catalyst for complex formation. Nevertheless, the ether was used as the medium for all iron powder runs because of its solvent action for ferric chloride and the smaller particle sizes which were obtained as a result of its use. 

Fig. 3.27. ATR spectra of DL-phenylalanine (powder, run on 1-mm KRS-5 plate directly). Solid line, room temperature dotted line, liquid-nitrogen temperature. (Parker, 1969.)...

The aldol condensation reaction demonstrates conversions on the order of 60% and selectivities to coupling products of 96% when carried out over the Ti02 (001)-[114] surface. The yield is increased even further on going to the [001] faceted Ti02 (001)-[001] surface and thus approaches those foimd over Ti02 powders (run under similar conditions). The patent hterature shows yields that are only slightly higher with 80% conversion and selectivities of 90%. 

The crude acetonitrile contains as impurity chiefly acetic acid, arising from the action of phosphoric acid on the acetamide. Therefore add to the nitrile about half its volume of water, and then add powdered dry potassium carbonate until the well-shaken mixture is saturated. The potassium carbonate neutralises any acetic acid present, and at the same time salts out the otherwise water-soluble nitrile as a separate upper layer. Allow to stand for 20 minutes with further occasional shaking. Now decant the mixed liquids into a separating-funnel, run off the lower carbonate layer as completely as possible, and then pour off the acetonitrile into a 25 ml, distilling-flask into which about 3-4 g. of phosphorus pentoxide have been placed immediately before. Fit a thermometer and water-condenser to the flask and distil the acetonitrile slowly, collecting the fraction of b.p. 79-82°. Yield 9 5 g. (12 ml.). 

Now transfer the cold distillate to a separating-funnel, and shake vigorously with about 50-60 ml. of ether run oflF the lower aqueous layer and then decantf the ethereal solution through the mouth of the funnel into a 200 ml. conical flask. Replace the aqueous layer in the funnel, and extract similarly twice more with ether, combining the ethereal extracts in the conical flask. Add 3-4 g. of dry powdered potassium carbonate to the ethereal solution, securely cork the flask and shake the contents gently. The ethereal solution of the phenol... 

A) Extract the mixture with about 40 ml. of chloroform, in which the free base is very soluble. Run off the lower chloroform layer, dry it with potassium carbonate as in (a), and then add carbon tetrachloride slowly with stirring to the filtered chloroform solution until the base starts to crystallise out. Allow to stand for a short time (t.e., until the deposition of crystals ceases) and then filter at the pump as the crystals lose the last trace of solvent, they tend as before to break up into a fine powder, the deep green colour becoming paler in consequence. 

A 1500 ml. flask is fitted (preferably by means of a three-necked adaptor) with a rubber-sleeved or mercury-sealed stirrer (Fig. 20, p. 39), a reflux water-condenser, and a dropping-funnel cf. Fig. 23(c), p. 45, in which only a two-necked adaptor is shown or Fig. 23(G)). The dried zinc powder (20 g.) is placed in the flask, and a solution of 28 ml. of ethyl bromoacetate and 32 ml. of benzaldehyde in 40 ml. of dry benzene containing 5 ml. of dry ether is placed in the dropping-funnel. Approximately 10 ml. of this solution is run on to the zinc powder, and the mixture allowed to remain unstirred until (usually within a few minutes) a vigorous reaction occurs. (If no reaction occurs, warm the mixture on the water-bath until the reaction starts.) The stirrer is now started, and the rest of the solution allowed to run in drop-wise over a period of about 30 minutes so that the initial reaction is steadily maintained. The flask is then heated on a water-bath for 30 minutes with continuous stirring, and is then cooled in an ice-water bath. The well-stirred product is then hydrolysed by the addition of 120 ml. of 10% sulphuric acid. The mixture is transferred to a separating-funnel, the lower aqueous layer discarded, and the upper benzene layer then... 

Or altcrmtiTclr add powdered sodium chloride w ith stirring in order to salt out" the araiuc, and then run off the lower aqiieous layer. 

To the remainder of the casein solution add 0 5 to o 8 g. of finely powdered commercial trypsin, shake to dissolve, and place in a thermostat (or in an incubator) at 40 . After 15 minutes, remove 25 ml. and add a few drops of phenolphthalein it will now be found that the solution remains colourless. Run in carefully Mj 10 NaOH solution until the colour of the solution is just pink, add 5 ml, of neutralised formalin and then titrate against Mj 10 NaOH solution until the pink colour is just restored note the amount required. Remove fiirther quantities (rf 25 ml. at intervals which must be determined by the speed of the reaction. The following will probably make a suitable series i, 2, 3,... 

In a 1-litre three-necked flask, fitted with a mechanical stirrer, reflux condenser and a thermometer, place 200 g. of iodoform and half of a sodium arsenite solution, prepared from 54-5 g. of A.R. arsenious oxide, 107 g. of A.R. sodium hydroxide and 520 ml. of water. Start the stirrer and heat the flask until the thermometer reads 60-65° maintain the mixture at this temperature during the whole reaction (1). Run in the remainder of the sodium arsenite solution during the course of 15 minutes, and keep the reaction mixture at 60-65° for 1 hour in order to complete the reaction. AUow to cool to about 40-45° (2) and filter with suction from the small amount of solid impurities. Separate the lower layer from the filtrate, dry it with anhydrous calcium chloride, and distil the crude methylene iodide (131 g. this crude product is satisfactory for most purposes) under diminished pressure. Practically all passes over as a light straw-coloured (sometimes brown) liquid at 80°/25 mm. it melts at 6°. Some of the colour may be removed by shaking with silver powder. The small dark residue in the flask solidifies on cooling. 

Conduct the preparation in the fume cupboard. Dissolve 250 g. of redistilled chloroacetic acid (Section 111,125) in 350 ml. of water contained in a 2 -5 litre round-bottomed flask. Warm the solution to about 50°, neutralise it by the cautious addition of 145 g. of anhydrous sodium carbonate in small portions cool the resulting solution to the laboratory temperature. Dissolve 150 g. of sodium cyanide powder (97-98 per cent. NaCN) in 375 ml. of water at 50-55°, cool to room temperature and add it to the sodium chloroacetate solution mix the solutions rapidly and cool in running water to prevent an appreciable rise in temperature. When all the sodium cyanide solution has been introduced, allow the temperature to rise when it reaches 95°, add 100 ml. of ice water and repeat the addition, if necessary, until the temperature no longer rises (1). Heat the solution on a water bath for an hour in order to complete the reaction. Cool the solution again to room temperature and slowly dis solve 120 g. of solid sodium hydroxide in it. Heat the solution on a water bath for 4 hours. Evolution of ammonia commences at 60-70° and becomes more vigorous as the temperature rises (2). Slowly add a solution of 300 g. of anhydrous calcium chloride in 900 ml. of water at 40° to the hot sodium malonate solution mix the solutions well after each addition. Allow the mixture to stand for 24 hours in order to convert the initial cheese-Uke precipitate of calcium malonate into a coarsely crystalline form. Decant the supernatant solution and wash the solid by decantation four times with 250 ml. portions of cold water. Filter at the pump. 

Add 25 g. of finely-powdered, dry acetanilide to 25 ml. of glacial acetic acid contained in a 500 ml. beaker introduce into the well-stirred mixture 92 g. (50 ml.) of concentrated sulphuric acid. The mixture becomes warm and a clear solution results. Surround the beaker with a freezing mixture of ice and salt, and stir the solution mechanically. Support a separatory funnel, containing a cold mixture of 15 -5 g. (11 ml.) of concentrated nitric acid and 12 -5 g. (7 ml.) of concentrated sulphuric acid, over the beaker. When the temperature of the solution falls to 0-2°, run in the acid mixture gradually while the temperature is maintained below 10°. After all the mixed acid has been added, remove the beaker from the freezing mixture, and allow it to stand at room temperature for 1 hour. Pour the reaction mixture on to 250 g. of crushed ice (or into 500 ml. of cold water), whereby the crude nitroacetanilide is at once precipitated. Allow to stand for 15 minutes, filter with suction on a Buchner funnel, wash it thoroughly with cold water until free from acids (test the wash water), and drain well. Recrystallise the pale yellow product from alcohol or methylated spirit (see Section IV,12 for experimental details), filter at the pump, wash with a httle cold alcohol, and dry in the air upon filter paper. [The yellow o-nitroacetanihde remains in the filtrate.] The yield of p-nitroacetanihde, a colourless crystalline sohd of m.p. 214°, is 20 g. 

Low-pressure hysteresis is not confined to Type I isotherms, however, and is frequently superimposed on the conventional hysteresis loop of the Type IV isotherm. In the region below the shoulder of the hysteresis loop the desorption branch runs parallel to the adsorption curve, as in Fig. 4.26, and in Fig. 4.2S(fi) and (d). It is usually found that the low-pressure hysteresis does not appear unless the desorption run commences from a relative pressure which is above some threshold value. In the study of butane adsorbed on powdered graphite referred to in Fig. 3.23, for example, the isotherm was reversible so long as the relative pressure was confined to the branch below the shoulder F. 

There are many techniques available for measuring the particle-size distribution of powders. The wide size range covered, from nanometers to millimeters, cannot be analyzed using a single measurement principle. Added to this are the usual constraints of capital costs versus running costs, speed of operation, degree of skill required, and, most important, the end-use requirement. 

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