Boring of corks

Fit apparatus together carefully and compactly, paying particular attention to the clamping that holds the apparatus steady and to the fitting and boring of corks and stoppers. 

Boiling-point composition curves, 7-12 Bond refractions, 1036 Boring of corks, 55, 56 Boron trifluoride, 183, 862, 864, 865 Bouveault-Blanc reduction, 247, 249, 250, 812, 832... 

Boring of Corks.—Sharp borers should always be used. The end of the cork is placed against some solid object and bored half-way through from one end. The boring should then be completed from the other end. The boring of rubber stoppers may be greatly facilitated by moistening the borer with caustic soda. Mechanical borers are now available. 

II.l INTRODUCTION Before the student attempts to carry out the analytical reactions of the various cations and anions detailed in Chapters III and IV, he should be familiar with the operations commonly employed in qualitative analysis, that is with the laboratory technique involved. It is assumed that the student has had some training in elementary practical chemistry he should be familiar with such operations as solution, evaporation, crystallization, distillation, precipitation, filtration, decantation, bending of glass tubes, preparation of ignition tubes, boring of corks, and construction of a wash bottle. These will therefore be either very briefly discussed or not described at all in the following pages. 

Such an assembly dispenses with the use of corks. Ground-glass-joint assemblies can be set up on command as no time-consuming jobs like boring of corks etc. are involved and, also, these assemblies are leak-proof straight away. Further, the probability of the undesirable situation arising from reaction between the substance... 

Alternatively a mercury-sealed stirrer may be employed. Here again a short glass tube C is inserted through the cork of the flask to act as a collar for the stirrer. The tube C carries a short wide tube B which is either fused at its lower end to C, or is fixed to it by means of a cork as shown. The stirrer D carries a precisely similar tube E, the top of which however is now fixed to D the bore of the tube E allows it to fit easily within the annular space between the collar C and the tube B. Mercury... 

The selection, boring, and fltting of corks is largely eliminated, thus resulting in a considerable saving of time. 

Wider passages are provided for vapours and the comparatively narrow tubes, which are usually fitted through holes bored in cork or rubber stoppers, are absent this considerably diminishes danger in violent reactions and also tends to give better results in distillation under reduced pressure as well as diminishing the hazard of choking. ... 

The capillary tube is inserted (with a little glycerol as lubricant), tip first, into a narrow-bored, undamaged rubber stopper which fits tightly into the neck a of the Claisen flask. The correct position of the tip is immediately above the deepest part of the bulb of the flask. A thermometer, likewise pushed through a rubber stopper, is inserted into the neck b. If it is desired to prevent contact of the substance with rubber, Claisen flasks with constricted necks are used. The capillary tube and thermometer are held in position in these necks by means of small pieces of rubber tubing drawn over each neck and its capillary or thermometer. The proper use of cork stoppers in vacuum distillations requires much practice. 

Freshly opened cans of anhydrous ether (Fisher) were used in the extraction process. Efficient drying over MgSC>4 (under nitrogen) is needed to avoid excessive loss of product in the forerun as a product/water azeotrope. The one-hole rubber septum used for ihe transfer process was obtained by using a cork bore of the appropriate size on a 24/40 rubber septum (Aldrich Chemical Company, Inc.). Rotary evaporation to remove the ether was carried out at 200-300 mbar (150-225 mm)... 

Continuous steam distillation, 147, 148 Cooling baths, 61 Cooling curve method, 26 Copper bronze, activated, 193 Copper - chromium oxide catalyst, for aldehyde synthesis, 318, 321 for hydrogenation, 872, 873 hydrogenolysis with, 872J Copper phthalocyanine, 983 Copper powder, 192 Copper sulphate, as desiccant, 40, 41 Cork stoppers, 55 boring of, 56... 

The spindle of the outer tube can be drawn off, the end rounded to perfect hemispherical shape, and the end tube 2 joined on to a hole pierced at this end (2), The inner tube being held by its spindle, its square-cut end is enlarged to cover the bore of the outer, and then closed with its cork and tube its spindle is then drawn off and the end blown hemispherical. The inner tube when cold can be slipped into the outer, the ends in contact fused all round, and the joint worked uniform and smooth as above. The heating should be only right on the end face, and tendencies of the inner tube to project out or bulge at the neck must be rectified as before by the use of the stick and the spinning tool, as indicated in Fig. 25 (4), and explained above. 

In oidec to propare ibe a flask provided with a doubly bored eaontcboao cork, Pig. 37, made use of febioujfli (me tbe ludes a gas delivery-tube is fixed, whilst through the olber a stoppered funnel tube is passed. A mixture of one part by weight of amorphoos phosphorus and two parts of wato is intioduced into the tesk, and ten parts of bromine are allowed to fall drop by drop Qiron the stoppered fUnnel-tube on to the mixture... 

These advantages include (a) Speed of assembly, (b) Well-fitting joints as these are made to accurate standards and joints of any given size are thus interchangeable, (c) Accurate alignment of assembly, for the use of incorrectly bored corks is obviated, d) Freedom from contamination of liquids by cork and rubber. 

Assemble the apparatus shown in Fig. 6o. A is a 500 ml. bolt-head flask connected by a knee-tube B to a water-condenser C, to the lower end of which is fitted the adaptor D. In view of the low boiling-point of the ethyl bromide, it is essential that the various portions of the apparatus are connected together by well-bored, tightly fitting corks. (For this reason, the apparatus shown in Fig. 23(0), p. 45, is preferable.)... 

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