Towel rings

Slip the front and rear brake ring/ collar assemblies onto the launch tube ends. Tap into final position with a wooden block if necessary. Protect the central tube area with a damp towel before welding the front and rear collars into place. 

Add 50 mL of 3M sodium hydroxide solution, shake thoroughly, and separate the aqueous layer. Extract with a further 25-mL portion of aqueous alkali and combine the extracts. Wash with 10 mL of water, and add this aqueous solution to the 75 mL of aqueous extract already collected. Discard the benzene-ether solution. Acidify the 85 mL of combined alkaline extract with concentrated hydrochloric acid to pH 1 -2 and, if the o-benzoylbenzoic acid separates as an oil, cool in ice and rub the walls of the flask with a stirring rod to induce crystallization of the hydrate collect the product and wash it well with water. This material is the monohydrate CeH5C0QH4C02H HjO. To convert it into anhydrous o-benzoylbenzoic acid, put it in a tared, 250-mL round-bottomed flask, evacuate the flask at the full force of the aspirator, and heat it in the open rings of a steam bath covering the flask with a towel. Check the weight of the flask and contents for constancy after 45 min, 1 h, and 1.25 h. The yield is usually 19-21 g, mp 126-127°C. 

Preparation, (a) Place 12.8 g. of trichloroacetic acid in a 125-ml. Erlenmeyer with a side arm and, with cooling in an ice bath, pour in about nine tenths of an ice cold solution of 3.2 g. of sodium hydroxide pellets in 12 ml. of water. Add a drop of 0.04% Bromocresol Green solution to produce a faint yellow color, and with a capillary dropping tube titrate the solution to an end point where a single drop produces a change from yellow to blue. Close the flask with a rubber stopper, mount it within the rings of a steam bath and wrap a towel around it for maximal heat, connect it to the suction pump, and turn on the water at full speed. The evaporation needs no attention and can be completed in 15-20 minutes. The weight of dry powder is close to the theory (14.5 g.). 

Clean a porcelain crucible and lid with soapy water and a brush. Rinse thoroughly and dry with a paper towel. Set up a ring stand and ring with a clay triangle for heating the crucible and lid with a Bunsen burner flame as in Experiment 15 and proceed to prepare the crucible and lid as directed in Experiment 15. Allow to cool for 15 minutes and weigh. 

Use tongs or a cloth towel and remove the graduated cylinder from the oven. Hold it in place on a ring stand with a buret clamp. Fill it to about 80 mL with the hot water. 

Ring, cork, 7.5 cm dia. Ring, iron, 10 cm Stand, ring Towel or sponge. Transformer, variable Trap, Barrett, 20 mL, 24/40 joints Tubing, condenser Wire, copper... 

Rack, vacuum, 4 ft long, 3 ft high A inch rods 3,4 ft rods, 4, 3 ft rods Receiver, udder type Refractometer, Abbe Ring, cork, 250 mL Rings, cork, 50 mL Sacks, paper, to get dry ice in Stopcock, straight, 2 mm Stopper, rubber, 1 hole. No. 3 Stopper, rubber, 1 hole. No. 7 Strip, terminal, 3 port minimum Support rack, stirring motor rack 10/30 Thermometer, 5 cm immersion, -10 to 150 C Towel to crush dry ice in Transformers, variable Traps, vapor... 

Stand, ring 1 Towel, cloth 3 m Tubing, condenser 30 cm Wire, copper... 

Refer to Figure E36-I. It can all be set up on one ring stand. The apparatus often will become covered with a white solid. This is ammonium chloride and will wipe away easily with a wet towel and is not harmful. 

Paper, filter, 11 cm, medium Pipet, Mohr, 5 mL Sponge or cloth towel Stand, ring Stirrer, magnetie Syringe, 10 mL... 

Razor blade, single edge 1 Rod, stirring 1 Stand, ring 1 Tongs, long handle 1 Towel, cloth... 

Place together the Cap2 windows (wrapped loosely in a piece of lens paper), the PTFE tube, a Pasteur pipette, the tweezers, the aluminium tools and PTFE cylinder, the degassed sample of the solution to be analysed (usually in a round-bottomed flask), and the cork ring on a piece of paper towelling in the vessel which fits into the evacuating chamber of the dry box. 

Introduce the vessel to the chamber of the dry box and assemble the equipment on the paper towelling on a flat surface in the dry box (the base). Support the sample solution on the cork ring and open it to the inert atmosphere. 

Incubations of microscope slides with small amount of incubation solution must be done in a closed box with a source of water vapor (moist paper towels) to prevent the small volume of solution from drying. While it is possible to buy boxes, most researchers like to make their own with recycled plastic boxes from lab products. Incubation times are generally 24-48 h. Evaporation of the small volumes is a major problem. Agitation, while needed to shorten the incubation time, is not used because of the danger that the incubation solution will run outside the rings. 

Using a forceps and a knife, take some sodium from the storage container, cut a small piece about the size of a small pea (3 mm on a side), and dry it on a paper towel. Place this small piece of sodium in a clean, dry, small test tube (10 mm x 75 mm). Clamp the test tube to a ring stand, and heat the bottom of the tube with a microburner until... 

FILL THE CRACK. Now reverse the process, using the syringe to slowly add resin to the vacuum you created in the crack. Before the resin dries, have paper towels at the ready and use a razor blade to scrape free the adhesive ring. Dab the adhesive that oozes out with the paper towels. 

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