Water free-draining

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. 

As mentioned above, insulation applied to externally located equipment can be subjected to rain and weather contamination if the outer cladding fails. Insulants with water-repellant, water-tolerant or free-draining properties offer an additional benefit in this type of application. In the structural field insulants used as cavity wall fills must be of those types specially treated and designed for this application. 

It comes as no surprise, perhaps, that fruit prefers deep, rich loam that is free-draining but moisture-retentive. You may not have these conditions at first, but much can be done to improve soil structure, open up heavy soil, and increase the water-holding capacity of light soil (see The Soil, pp.34-35). If starting with very poor soil, start to improve it a year in advance of planting fruit trees or bushes. 

Deaton and Frost (1946) suggested the same apparatus could be used for conditions below the ice point. In these experiments, gas was first bubbled through water above 273 K, to form a honeycomb mass of hydrate. Then free water was drained before the cell was cooled below the ice point. After the temperature was stabilized, gas was removed in small increments until a region of constant pressure was obtained, which indicated dissociation of the hydrate phase. Deaton and Frost used this procedure only for equilibria of simple hydrates, since the hydrated mass of guest mixtures was not constrained to be of uniform composition, and consequently would have decomposed at different pressures. 

Cool the beaker in a bath of cold water and add 150 ml of cold water. Filter off the crude phenanthraquinone with suction and wash it with water until free from chromium salts. Suspend the solid in 20 ml of rectified spirit and add, with stirring, 20 ml of saturated sodium metabisulphite solution. Break up the lumps of the addition product with a glass rod and allow to stand, with frequent stirring, for 10 minutes. Add 150 ml of water to dissolve the addition product and filter with suction. Reject the precipitate which consists of the impurities present in the phenanthrene. Add saturated sodium carbonate solution to the filtrate until the bisulphite addition product is completely decomposed allow the precipitate to settle for 1 minute, then add a few drops of sodium carbonate solution and note whether any further precipitation occurs. Stir the precipitate for 2-3 minutes, filter with suction, wash with three 20 ml portions of water and drain well. Dry the product between filter papers and then in a desiccator over calcium chloride. The yield of phenanthraquinone, m.p. 206 °C, is 1.4 g (60%). The product may be recrystallised from glacial acetic acid (about 20 ml), but the m.p. is unaffected. 

The solute-water interaction extends 1-3 nm (Israelachvili, 1992) and decays exponentially with distance (Van de Ven, 1989). Non-free-draining water is water within this distance traveling with the same velocity as the particle nucleus. At the interface between the non-free-draining (bound) water and the outer volume of free-draining water traveling at a different velocity, an fc [Eq. (3.27)] is generated. In this sense, hydration and the imaginary shear plane have enormous ramifications for human oral sensations elicited by dispersed polysaccharides. 

A sediment is a solid phase separated from its dispersion medium in a relatively solvent-free condition the process is called sedimentation or deposition. The rate of sedimentation depends on T]n, cj), M, particle size, and the density difference between the solvent and solute (Scholte, 1975 Harding et al., 1991a). The density of highly hydrated particles is approximately equal to the density of water a large volume of non-free-draining water may therefore cause a floe to remain suspended almost indefinitely. Very small density differences do not provide enough of a gradient to affect rapid deposition. 

The non-free-draining water attached to a polysaccharide molecule and the free-draining water surrounding it travel at different velocities across a boundary whose location is a function of fc and, therefore, a function of Rg and ti0 [Eq. (4.1) Flory, 1953 Tanford, 1961] ... 

Assay Prepare an acetylating reagent, within one week of use, by mixing 3.4 mL of water and 130 mL of acetic anhydride with 1000 mL of anhydrous pyridine. For the Assay, pipet 20 mL of this reagent into a 250-mL iodine flask, and add about 1 g of sample, accurately weighed. Attach a dry reflux condenser to the flask, and reflux for 1 h. Allow the flask to cool to room temperature, then rinse the condenser with 50 mL of chilled (10°) carbon dioxide-free water, allowing the water to drain into the flask. Stopper the flask, cool to below 20°, add... 

Put the SAC resin into the column. Regenerate it with 3 BV of 2. N HCI lollowed by 2 B of 5. N HCI. Rinse until add free with deionized water and drain to 6 mm above bed level. To remove trace metals and ensure that the resin is fully in the hydrogen form, a large excess of regenerant is used. 

This process comprises dissolution of alumino-silicate minerals, and is the basis for much of the discussion concerning the development of saprolites and associated weathering products. Although conditions at the weathering front may initially favour the formation of micaceous clays (e.g. chlorite, vermiculite) and smectite, small quantities of gibbsite may also be formed, and, eventually, kaolinite can come to dominate those free-draining profiles where there is an adequate water supply. 

---