Mortar, 2.24

For this preparation, it is particularly necessary that the sodium acetate should be free from traces of water. The anhydrous material can be prepared by gently heating the hydrated salt (CHsCOONa,3HjO) in an esaporating-basin over a small Bunsen flame. The salt dissolves in its water of ciystallisation and resolidifies as this water is driven off further heating then causes the anhydrous material to melt. Stir the molten anhydrous material to avoid charring, and then allow it to cool in a desiccator. Powder the cold material rapidly in a mortar, and bottle without delay. 

CAUTION. The vapour of selenium dioxide is poisonous, and all operations involving the hot material, alone or in solution, should be performed in a fume-cupboard. If lumps of selenium dioxide have to be powdered in a mortar, the latter should also be in a fume-cupboard, with the window lowered as far as possible, to avoid inhaling the fine dust. (cf. p. 191)... 

Lithium aluminium hydride if carelessly manipulated may be dangerous for two distinct reasons. The material is caustic, and should not be allowed to touch the skin it is particularly important that the finely divided material should be kept away from the lips, nostrils and eyes, and consequently pulverisation in a mortar must be carried out with the mortar in a fume-cupboard, and with the window drawn down as far as possible in front of the operator. This danger from handling has however been greatly reduced, for the hydride is now sold in stated amounts as a coarse powder enclosed in a polythene bag in a metal container this powder dissolves readily in ether, and preliminary pulverisation is unnecessary. 

Mix 6 2 ml. (6 4 g.) of pure ethyl acetoacetate and 5 ml. of pure phenylhydrazine in an evaporating-basin of about 75 ml. capacity, add 0 5 ml. of acetic acid and then heat the mixture on a briskly boiling water-bath (preferably in a fume-cupboard) for I hour, occasionally stirring the mixture with a short glass rod. Then allow the heavy yellow syrup to cool somewhat, add 30-40 ml. of ether, and stir the mixture vigorously the syrup may now dissolve and the solution shortly afterwards deposit the crystalline pyrazolone, or at lower temperatures the syrup may solidify directly. Note. If the laboratory has been inoculated by previous preparations, the syrup may solidify whilst still on the water-bath in this case the solid product when cold must be chipped out of the basin, and ground in a mortar with the ether.) Now filter the product at the pump, and wash the solid material thoroughly with ether. Recrystallise the product from a small quantity of a mixture of equal volumes of water and ethanol. The methyl-phenyl-pyrazolone is obtained... 

Now grind up the mixture of solution and glass in the mortar to ensure extraction of the sodium salts, and then filter. Divide the filtrate into three portions, reserving two portions for testing for halogens and sulphur. 

Preparation of the Reagent. Grind thoroughly together in a dry mortar 25 g. of pure anhydrous ( Analar ) sodium carbonate and 50 g. of the purest obtainable zinc dust. Preserve the reagent in a wide-necked stoppered bottle until required. 

Mix about 0 2 g. of each of the following powdered substances with about i g. of powdered soda-lime, preferably by grinding in a small clean mortar. The odour of ammonia in the cold usually indicates an ammonium ... 

The furnace and thermostatic mortar. For heating the tube packing, a small electric furnace N has been found to be more satisfactory than a row of gas burners. The type used consists of a silica tube (I s cm. in diameter and 25 cm. long) wound with nichrome wire and contained in an asbestos cylinder, the annular space being lagged the ends of the asbestos cylinder being closed by asbestos semi-circles built round the porcelain furnace tube. The furnace is controlled by a Simmerstat that has been calibrated at 680 against a bimetal pyrometer, and the furnace temperature is checked by this method from time to time. The furnace is equipped with a small steel bar attached to the asbestos and is thus mounted on an ordinary laboratory stand the Simmerstat may then be placed immediately underneath it on the baseplate of this stand, or alternatively the furnace may be built on to the top of the Simmerstat box. 

The thermostatic mortar P, whose function is described below, is a small electrical heating unit (1 5 cm. in diameter and 7 cm. long) kept constant at 180 . The temperature is kept constant by another Simmerstat. The mortal may be supported on its Simmerstat box or alternatively screwed on to the end of the furnace, a gap of 1 cm. being left between the furnace and the mortar in each case. The right-hand end of the mortar bore is only wide enough to take the drawn-out beak end of the combustion tube, which is thus held in place. 

There is a tendency for the water produced by the combustion to condense in the narrow neck of the combustion tube, instead of passing right over into the absorption tube. To avoid this, two movable copper hooks Q are mounted on a copper rod, which can slide in and out of a hole cut in the mortar P these may be placed over the beak of the combustion tube and conduct sufficient heat from the mortar to vaporise the water once again so that it is driven over by the Oxygen stream into the absorption tube R. 

The oxygen is turned on, tap Tj carefully opened and the furnace N and the thermostatic mortar P then turned on. The apparatus can conveniently be allowed to attain its equilibrium temperature over the period of about 20 minutes while the absorption tubes are being polished and weighed and the specimen for andysis weighed out it is thus ready for immediate use as soon as the weighings have been completed. 

At the end of the sweeping out, the tap Ti is first closed, and then the taps T3, T4, Ts and Tj in this order. The tubes R and S are then detached from the beak of the combustion tube, the guard tube V is then detached from them and replaced on the combustion tube beak. The furnace and thermostatic mortar are then switched off and the combustion tube allowed to cool with the tap to the oxygen supply open. The bung J is removed, and the boat withdrawn by means of a piece of rigid copper wire with a small hook in the end that fits into the small hole in the lip at the back of the boat the bung is then replaced and the boat transferred to its block in the desiccator. 

In preparing this mixture, the lactose and the potassium nitrate should be powdered separately and then mixed solely by shying. They should not be ground together in a mortar. 

Grind 10 g. of malt thoroughly in a mortar so that the grains are completely pulverised, add 50 ml. of water and macerate well. Allow to stand for about one hour, grinding up the mixture thoroughly from time to time, and then Biter through a Buchner funnel. 

Urease solution. Place about 5 g. of jack-bean meal in a mortar and grind up with about 10 ml. of water, t hen add about 90 ml. of water, mix thoroughly and allow to stand for some time in order to deposit starch and other insoluble substances. Decant off the supernatant liquid into a conical flask and cork the latter. 

Place about o-i g. (or 0 1 ml.) of the amine in a test-tube, add o-i ml. of glacial aatic acid to dissolve the amine and then add water until the test-tube is half-full Next place about 0 3 g. of the peroxidase preparation in a very small mortar and grind up with about 15 ml. of water. Filter through a small fluted filter-paper into a test-tube. 

It should be emphasized at this point that the basic requirements of compatibility and consistency of finite elements used in the discretization of the domain in a field problem cannot be arbitrarily violated. Therefore, application of the previously described classes of computational grids requires systematic data transfomiation procedures across interfaces involving discontinuity or overlapping. For example, by the use of specially designed mortar elements necessary communication between incompatible sections of a finite element grid can be established (Maday et ah, 1989). 

Maday, Y., Mavripilis, C. and Petera, A. T., 1980. Nonconforming mortar element methods application to. spectral discretizations. In Chan, T. F, Glowinski, R., Perianx, J. and Widlund, O. B. (eds). Domain Decomposition Methods, SIAM, Philadelphia, pp. 392- 418. 

Sodium amalgam. The amalgam which is generally employed for reductions contains from 1 to 3 per cent, of sodium. Amalgams with a greater sodium content than 1 2 per cent, are solid at the ordinary temperature and can be powdered in a mortar the 1 2 per cent, amalgam is semi-solid at room temperature but is completely fluid at 50°. Two methods of preparation are available. 

Sodamide may be readily pulverised by grinding in a glass mortar under an inert hydrocarbon solvent (benzene, toluene, xylene, etc.). 

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