Mean of runs

Place the wet crude salt in a beaker, cool by means of running water, and add (using the hood) sufficient solution of 30 per cent sodium hydroxide to decompose the salt and cause the base to rise as an oil to the top. Avoid breathing the fumes given off by phenylhydrazine, as they are very toxic. Cool, and transfer to a separatory funnel, washing the beaker with 20 ml of ether. Extract twice with 50-ml portion of ether, and dry the ethereal solution of the base with solid sodium hydroxide. Transfer the ether solution into a 250-ml Claisen flask and distill off the ether by means of a water bath. Remove the bath, and arrange for distillation under reduced... 

Kessler s Reagent (Koch and McMeekin, 1924). Dissolve 22 5 gm. of iodine in 20 ml. of water containing 30 gm. of potassium iodide. Keeping the mixture cool by means of running water, add 30 gm. of mercury, and shake until the yellow colour has disappeared. 

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... 

Transport of France reduces dimensional change by using a thin inner liner of Invar. Another patented French system accommodates this change by means of the flexibility of thin metal which is creased. The creases run in two direc tions, and the form of the crossings of the creases is a feature of the system. 

Generahzed correlations are available for each of the operations which make up the full filter cycle. This means that simulated operating conditions can be varied to obtain a maximum of information without requiring an excessive number of test runs. The minimum number of test runs required for a given feed will, of course, vary with the expertise of the experimenter and the number of operations performed during the filter cycle. If, for example, the operation invdves only the dewatering of a slurry which forms a cake of relatively low to moderate porosity, frequently sufficient data can be obtained in as little as six runs. For more difficult tests, more runs are usually advisable, and the novice certainly should make a larger number of runs as there is likely to be more data scatter. 

Column Chromatography. The substances to be purified are usually placed on the top of the column and the solvent is run down the column. Fractions are collected and checked for compounds using TLC (UV and/or other means of visualisation). The adsorbent for chromatography can be packed dry and solvents to be used for chromatography are used to equilibrate the adsorbent by flushing the column several times until equilibration is achieved. Alternatively, the column containing the adsorbent is packed wet (slurry method) and pressure is applied at the top of the column until the column is well packed (i.e. the adsorbent is settled). 

First, the test described above must be run. Then a known air leak must be introduced to the system. This can be done by means of a calibrated air orifice. A second test is made, obtaining a new pressure rise and time. The unknown leak is then given by... 

Turn off the source of the leak and limit the spread of fluid by means of mop, dusters, rags, sand or diversion Absorb spillage and shovel into buckets, and remove to a safe place, dilute greatly with running water and/or dilute with dispersing agent and water (as with ammonia solution, ethanol, methanol and formaldehyde solution)... 

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