Two-hole

Several forms of apparatus employing electrical heati iig wi 11 be described. A simple form may be readily constructed from a domestic electric iron of 400-500 watts rating. The handle is removed, and two holes of 8 mm. diameter are drilled through the base (ca. 11 mm. thick) so that they meet in the centre of the block. One hole is for a 360° thermometer (small bulb) the other hole is spare and can be used for comparison with a standard thermometer. The heater is mounted on a sheet of thick asbestos board which is fixed to an appropriate wooden base. The wires from the heating unit are connected to two insulated terminals fitted on the board (Fig. 11, 11, 1). The rate of heating is controlled by either of the following methods ... 

Alternatively, a flask (capacity one litre or more), fitted with a two-holed cork carrying a long safety tube and a short right-angled bend, may be used. A large distilling flask will serve the same purpose. 

Ethyl Bromide. Fit a 1-litre round-bottomed flask with a two holed cork carrying a separatory funnel and a wide (6-8 mm.) bent tube connected to a long efficient condenser set for downward distillation (Fig. 111,35,1) alternatively, Fig. Ill, 35, 1. a two-way addition tube (Fig. 11, 1, 8)... 

Assemble the apparatus shown in Fig. Ill, 56, 1. Fit the 500 ml. distilling flask with a two-holed cork carrying a thermometer reaching to... 

Mix 50 ml. of formalin, containing about 37 per cent, of formaldehyde, with 40 ml. of concentrated ammonia solution (sp. gr. 0- 88) in a 200 ml. round-bottomed flask. Insert a two-holed cork or rubber stopper carrying a capillary tube drawn out at the lower end (as for vacuum distillation) and reaching almost to the bottom of the flask, and also a short outlet tube connected through a filter flask to a water pump. Evaporate the contents of the flask as far as possible on a water bath under reduced pressure. Add a further 40 ml. of concentrated ammonia solution and repeat the evaporation. Attach a reflux condenser to the flask, add sufficient absolute ethyl alcohol (about 100 ml.) in small portions to dissolve most of the residue, heat under reflux for a few minutes and filter the hot alcoholic extract, preferably through a hot water fuimel (all flames in the vicinity must be extinguished). When cold, filter the hexamine, wash it with a little absolute alcohol, and dry in the air. The yield is 10 g. Treat the filtrate with an equal volume of dry ether and cool in ice. A fiulher 2 g. of hexamine is obtained. 

Method 1 (with acetyl chloride). Equip a dry 500 ml. round-bottomed or bolt-head flask with a reflux condenser, and fit the top of the condenser with a two hole cork, one opening for a separatory funnel and the other for a delivery tube connected to an inverted funnel which dips just below the surface of about 200 ml. of water in a beaker (compare Fig. II, 13, 8). Place 40 g. of anhydrous, finely-powdered aluminium chloride (see Section IV,2) and 88 g. (100 ml.) of dry A.R. benzene in the flask and cool the latter in a bath of cold water (not ice water since benzene may crystallise). Through the separatory funnel at the top of the condenser add 29 g. (27 ml.) of redistilled acetyl chloride slowly during half an hour and shake the flask frequently to ensure thorough mixing of the... 

Place 150 g. of benzoic acid, 150 g. (139 ml.) of acetic anhydride and 0-2 ml. of syrupy phosphoric acid in a 500 ml. bolt-head flask. Fit the latter with a two-holed stopper carrying a dropping funnel and an efficient fractionating column (compare Fig. 7/7, 61, 1) it is advisable to lag the latter with asbestos cloth. Set up the flask in an oil bath or in a fusible metal bath. Distil the mixture very slowly and at such a rate that the temperature of the vapour at the head of the column does... 

Ethyl p-aminobenzoate (esterification of p-aminobenzoic acid). Place 80 ml. of absolute ethyl alcohol in a 250 ml. conical flask equipped with a two-holed cork and wash-bottle tubes. Pass dry hydrogen chloride (Section 11,48,2) through the alcohol until saturated—the increase in weight is about 20 g.—and transfer the solution to a 250 ml. round-bottomed flask. Introduce 12 g. of p-aminobenzoic acid, fit a double surface condenser to the flask, and reflux the mixture for 2 hours. Upon... 

An empty wash-bottle, equipped with a two-holed nork, may be interposed between the mouth and the pycnometer for corrosive or poisonous liquids. 

The apparatus to use is seen in figure 13 which consists of a burette, thermometer, Erlenmeyer flask and a two-holed rubber stopper that has a small V-shaped wedge cut out of one side of the rubber stopper to allow the inside contents to vent. 31.5g of orangy-red fuming nitric acid (see chemicals section) is poured into the Erlenmeyer flask and the rubber stopper with its burette and thermometer is placed on to the... 

Flask F is provided with a two-hole cork stopper connected with tube E, and with tube G which connects with the first condenser II and may be of smaller bore than tubes C and E. H is. a. condenser with a 30-cm. water jacket. H is connected with I by means of an adapter. / is a i-l. round-bottom flask supported in a pan which is at first filled with ice and later used as a water bath. Flask I is fitted with a two-hole cork stopper carrying the adapter connected with condenser H and a Vigreux column K of 2-cm. diameter and a length of 30 cm. to the side arm. Flask I and condenser H are covered with black cloth (Note 2). The side arm of K is connected with a 90-cm. water-jacketed condenser L which leads into M through an adapter, iff is a 750-cc. Erlen-meyer flask immersed in an ice bath. Flask M is provided with a two-hole stopper connected with the adapter from L and an upright bulb condenser that is provided with a tube leading through a window or to a hood. 

The reaction mixture is now surrounded by an ice and salt mixture. The separatory funnel is replaced by a two-hole rubber stopper containing a thermometer (bulb immersed in the reaction mixture) and a glass tube the outer end of which is connected to a mercury trap (Note 3). When the temperature of the reaction mixture has fallen to 0°, the condenser is replaced by a tube 10 mm. in diameter and adjusted so the end is 50 nun. above the surface of the reaction mixture. The reaction mix-... 

A satisfactory way to accomplish the introduction of chlorine with minimal loss of the gas is to seal the reaction flask with a two-holed stopper equipped with a gas-inlet tube reaching just above the surface of the reaction mixture and an exit tube connected to a U-tube filled with mineral oil which is used as a gas-flow indicator. Chlorine is then introduced from the cylinder through a safety trap at such a rate as to maintain a small positive pressure in the reaction flask. 

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