Bathe


These are the silicones. According to the degree of cross-linking and length of the chain, they can be obtained in the form of oils or rubber-like solids. The silicone oils are not volatile on heating and can be heated to high temperatures without decomposition (and so are useful for high vacuum pumps and high-temperature oil baths)  [c.190]

When the filtration is complete, run about 25 ml. of the ether solution into A, and place under the latter a water-bath which has been brought to the boil at some considerable distance from the apparatus. (With large classes, or in crowded laboratories, the water-baths may well be heated in fume-cupboards, which are usually at a safe distance for this purpose from the working benches.) As the ether distils off from A, run in more of the solution from B, and thus continue until it appears that all the ether has been distilled off, and only aniline remains in A. To complete the latter stages of the distillation, it may be necessary to reheat the water-bath this should be done as before at a safe distance from the apparatus. Now detach the Buchner flask D, pour the contents into an ether residue bottle, and then replace C by an air-condenser finally replace the funnel B by a thermometer reading to at least 200°. Distil the residual aniline carefully by direct heating over a gauze, and collect the fraction boiling at 180-185°. During the early part of distillation, a small quantity of ether may come over although the recorded temperature may be well above its boiling-point hence ensure that the flame is kept well away from the open end of the condenser. Yield, 17 g.  [c.164]

Fit two similar 250 ml. conical flasks, A and B, with reflux water-condensers (using ground-glass joints or rubber stoppers) and connect the condensers in series as before over two water-baths. Prepare a mixture of 2 volumes of acetic anhydride and i volume of glacial acetic acid,  [c.453]

Sand. Buckets of dry sand for fire-extinguishing should be available in the laboratory and should be strictly reserved for this purpose, and not encumbered with sand-baths, waste-paper, etc. Most fires on the bench may be quickly smothered by the ample use of sand. Sand once used for this purpose should always be thrown away afterwards, and not returned to the buckets, as it may contain appreciable quantities of inflammable, non-volatile materials e.g., nitrobenzene), and be dangerous if used a second time.  [c.528]

Bathe, K. J., 1996. Finite Element Procedures, Prentice Hall, Englewood Cliffs, NJ.  [c.68]

Bathe, K. J., 1996. Finite Element Procedure, Prentice Hall, Englewood Cliff, NJ.  [c.207]

For temperatures above 100°, oil baths are generally used. Medicinal paraffin may be employed for temperatures up to about 220°. Glycerol and di-n-butyl phthalate are satisfactory up to 140-150° above these temperatures fuming is usually excessive and the odour of the vapours is unpleasant. For temperatures up to about 250° hard hydrogenated cotton seed oil, m.p. 40-60°, is recommended it is clear, not sticky and solidifies on cooling its advantages are therefore obvious. Slight discoloration of the hard oU at high temperatures does not affect its  [c.58]

Higher temperatures may be obtained with the aid of baths of fusible metal alloys, e.g.. Woods metal—4 parts of Bi, 2 parts of Pb, 1 part of Sn, and 1 part of Cu—melts at 71° Rose s metal—2 of Bi, 1 of Pb and 1 of Sn—has a melting point of 94° a eutectic mixture of lead and tin, composed of 37 parts of Pb and 63 parts of Sn, melts at 183°. Metal baths should not be used at temperatures much in excess of 350° owing to the rapid oxidation of the alloy this oxidation may be reduced by employing a small com mercial glue pot (Fig. II, a, 2), the outer pot containing the metal alloy. Before heating, the beaker should be held in a large luminous flame until it is covered with a deposit of carbon, which prevents the fused metal from adhering to the beaker the same result is obtained by coating the beaker with graphite.  [c.59]

The beaker and thermometer should be removed from the metal bath before the latter solidifies. Metal baths have the advantage that they do not smoke or catch fire they are, however, solid at the ordinary temperature and are usually too expensive for general use.  [c.59]

A shallow metal vessel containing sand, the so-called sand bath, heated by means of a flame, was formerly employed for heating flasks and other glass apparatus. Owing to the low heat conductivity of sand, the temperature control is poor the use of sand baths is therefore not  [c.59]

The elimination of the liquid baths and, in consequence, the absence of burns due to accidental breakage of the ordinary glass apparatus.  [c.81]

For successful fractional distillation, slow and even heating of the bath surrounding the flask is essential. This may be achieved by suitably designed electrically-heated air baths or by the use of oil baths provided  [c.221]

Lead is a bluish-white metal of bright luster, is very soft, highly malleable, ductile, and a poor conductor of electricity. It is very resistant to corrosion lead pipes bearing the insignia of Roman emperors, used as drains from the baths, are still in service. It is used in containers for corrosive liquids (such as sulfuric acid) and may be toughened by the addition of a small percentage of antimony or other metals.  [c.85]

When the filtration is complete, run about 25 ml. of the ether solution into A, and place under the latter a water-bath which has been brought to the boil at some considerable distance from the apparatus. (With large classes, or in crowded laboratories, the water-baths may well be heated in fume-cupboards, which are usually at a safe distance for this purpose from the working benches.) As the ether distils off from A, run in more of the solution from B, and thus continue until it appears that all the ether has been distilled off, and only aniline remains in A. To complete the latter stages of the distillation, it may be necessary to reheat the water-bath this should be done as before at a safe distance from the apparatus. Now detach the Buchner flask D, pour the contents into an ether residue bottle, and then replace C by an air-condenser finally replace the funnel B by a thermometer reading to at least 200°. Distil the residual aniline carefully by direct heating over a gauze, and collect the fraction boiling at 180-185°. During the early part of distillation, a small quantity of ether may come over although the recorded temperature may be well above its boiling-point hence ensure that the flame is kept well away from the open end of the condenser. Yield, 17 g.  [c.164]

Fit two similar 250 ml. conical flasks, A and B, with reflux water-condensers (using ground-glass joints or rubber stoppers) and connect the condensers in series as before over two water-baths. Prepare a mixture of 2 volumes of acetic anhydride and i volume of glacial acetic acid.  [c.453]

Sand. Buckets of dry sand for fire-extinguishing should be available in the laboratory and should be strictly reserved for this purpose, and not encumbered with sand-baths, waste-paper, etc. Most fires on the bench may be quickly smothered by the ample use of sand. Sand once used for this purpose should always be thrown away afterwards, and not returned to the buckets, as it may contain appreciable quantities of inflammable, non-volatile materials (e.g., nitrobenzene), and be dangerous if used a second time.  [c.529]

For an ideal gas and a diathemiic piston, the condition of constant energy means constant temperature. The reverse change can then be carried out simply by relaxing the adiabatic constraint on the external walls and innnersing the system in a themiostatic bath. More generally tlie initial state and the final state may be at different temperatures so that one may have to have a series of temperature baths to ensure that the entire series of steps is reversible.  [c.338]

A second recent development has been the application 46 of the initial value representation 47 to semiclassically calculate A3.8.13 (and/or the equivalent time integral of the flux-flux correlation fiinction). While this approach has to date only been applied to problems with simplified hannonic baths, it shows considerable promise for applications to realistic systems, particularly those in which the real solvent bath may be adequately treated by a fiirther classical or quasiclassical approximation.  [c.893]

Fit two similar 100 ml. conical flasks, A and B, with reflux water-condensers, using ground-glass joints or rubber stoppers. Connect up the water-condensers in series. Weigh the flask A, add about 1 g. of pure dry powdered phenol and weigh again. Now add 10 ml. of the acetylating mixture to the flask A, and also to the control flask B. Con -nect the flasks to the reflux condensers and heat both flasks on briskly boiling water-baths for 30 minutes. Then remove the water-baths, and pour 20 ml. of distilled water down each condenser, shaking the contents of each flask gently to ensure complete hydrolysis of the unchanged acetic anhydride. Finally cool each flask thoroughly in cold water and allow to stand for 10 minutes. Then titrate the contents of each flask with N.NaOH solution, using phenolphthalein as an indicator. A fine emulsion of phenyl acetate will form when the contents of the flask A are diluted, and should therefore be vigorously stirred throughout the titration to ensure that all the free acetic acid is extracted by the iV.NaOH solution.  [c.451]

The described operations count provides a guide to estimate the computational time required for reduction of a full n x n matrix to upper triangular form. However, the global set of equations in finite element analysis will always be represented by a sparse banded (it may also be symmetric) coefficient matrix. It is therefore natural to consider ways for the exclusion of zero terras from arithmetic operations during computer implementation of the Gaussian elimination method. An additional advantage of modification of the basic procedure to enable the forward reduction to be applied only to the non-zero terms is to reduce the storage (i.e. core) requirement. To take full advantage of this possibility it is imporhmt to optimize the global node numbering in the finite element mesh in a way that the maximum bandwidth of non-zero terms remains as small as possible and creation of zeros in the interior elements of the band is avoided. Efficient band solver procedures such as the active column or skyline reduction method are now available (Bathe, 1996) which provide maximum computer economy by restricting the number of operations and high-speed storage requirement.  [c.203]

An air bath may be readily constructed by the student from a commercial circular tin can (that from tinned fruit or food is quite suitable), and is very satisfactory for most work involving the heating of liquids of boiling point above 80° (or below this temperature if the liquidis non-inflammable). The top edge of the can is first smoothed and any ragged pieces of metal removed. A series of holes is then punched through the bottom, and a circular piece of asbestos (about 2-3 mm. thickness) of the same diameter as the can inserted over the holes. The body of the can is then wrapped with asbestos cloth which is bound securely in position by two wires near the top and bottom of the can respectively. A piece of asbestos board (2-4 mm. thickness) of diameter slightly larger than the top of the can is then obtained and a hole of suitable diameter made in its centre the asbestos is then cut diametrically. The two halves, which constitute the cover of the air bath, will have the shape shown in Fig. II, 5, 3, b. The diameter of the hole in the asbestos lid should be approximately equal to the diameter of the neck of the largest flask that the air bath will accommodate. The air bath, supported on a tripod, is heated by means of a Bunsen burner the position of a distilling flask, which should be clamped, is shown in Fig. II, 5, 3, a. The flask should not, as a rule, rest on the bottom of the bath. The student is recommended to construct three air baths for flasks of 50, 100 and 250 ml. capacity.  [c.60]

One of the disadvantages of oil and metal baths is that the reaction mixture cannot be observed easily also for really constant temperatures, frequent adjustment of the source of heat is necessary. These difficulties are overcome, when comparatively small quantities of reactants are involved, in the apparatus shown in Fig. II, 5,4 (not drawn to scale). A  [c.60]

Fit two similar 100 ml. conical flasks, A and B, with reflux water-condensers, using ground-glass joints or rubber stoppers. Connect up the water-condensers in series. Weigh the flask A, add about 1 g. of pure dry powdered phenol and weigh again. Now add 10 ml. of the acetylating mi.vture to the flask A, and also to the control flask B. Connect the flasks to the reflux condensers and heat both flasks on briskly boiling water-baths for 30 minutes. Then remove the water-baths, and pour 20 ml. of distilled water down each condenser, shaking the contents of each flask gently to ensure complete hydrolysis of the unchanged acetic anhydride. Finally cool each flask thoroughly in cold water and allow to stand for 10 minutes. Then titrate the contents of each flask with N.NaOH solution, using phenolphthalein as an indicator. fine emulsion of phenyl acetate will form when the contents of the flask A are diluted, and should therefore be vigorously stirred throughout the titration to ensure that all the free acetic acid is extracted by the A. NaOH solution.  [c.451]


See pages that mention the term Bathe : [c.18]    [c.38]    [c.76]    [c.122]    [c.144]    [c.176]    [c.182]    [c.242]    [c.343]    [c.361]    [c.1942]    [c.454]    [c.41]    [c.206]    [c.57]    [c.58]    [c.59]    [c.61]    [c.114]    [c.454]   
Practical aspects of finite element modelling of polymer processing (2002) -- [ c.41 , c.68 , c.203 , c.206 , c.207 ]