Test-tube clamp

An additional useful test is to distil the acid or its sodium salt with soda lime. Heat 0.5 g. of the acid or its sodium salt with 0 2 g. of soda lime in an ignition tube to make certain that there is no explosion. Then grind together 0-5 g. of the acid with 3 g. of soda hme, place the mixture in a Pyrex test-tube and cover it with an equal bulk of soda hme. Fit a wide dehvery tube dipping into an empty test-tube. Clamp the tube near the mouth. Heat the soda lime first and then the mixture gradually to a dull-red heat. Examine the product this may consist of aromatic hydrocarbons or derivatives, e.g., phenol from sahcyUc acid, anisole from anisic acid, toluene from toluic acid, etc. 

Cholestenone. Place a mixture of 1 0 g. of purified cholesterol and 0-2 g. of cupric oxide in a test-tube clamped securely at the top, add a fragment of Dry Ice in order to displace the air by carbon dioxide, and insert a plug of cotton wool in the mouth of the tube. Heat in a metal bath at 300-315° for 15 minutes and allow to cool rotate the test-tube occasionally in order to spread the melt on the sides. Warm with a few ml. of benzene and pour the black suspension directly into the top of a previously prepared chromatographic column (1) rinse the test-tube with a little more benzene and pour the rinsings into the column. With the aid of shght suction (> 3-4 cm. of mercury), draw the solution into the alumina column stir the top 0 -5 cm. or so with a stout copper wire to... 

Use the test-tube clamp to hold the test tube vertically in the boiling water bath. Make sure all of the naphthalene is below the surface of the boiling water. When the naphthalene has melted, insert the rubber stopper assembly into the top of the test tube. CAUTION The test tube may be hot. The thermometer should be immersed in the naphthalene. The stirring wire should loop around the thermometer. Move the stirring wire up and down to stir the contents of the test tube. Stir the naphthalene as it is being heated until all of the naphthalene has melted. 

Remove the test tube from the boiling water bath by repositioning the test-tube clamp so that it is no longer over the beaker. CAUTION The test-tube clamp may be hot. Monitor the temperature of the naphthalene as it cools. Continue stirring the naphthalene as it cools to ensure that the temperature is constant throughout. 

Reposition the test-tube clamp so that the test tube containing the solid naphthalene is again partially submerged in the boiling water bath. Heat the test tube until the naphthalene is melted and you can remove the thermometer and stirrer as a unit. CAUTION The thermometer, stirring wire, and test tube may be hot. Do not discard the naphthalene. Remove all the naphthalene from the stopper, thermometer, and stirrer by washing them with acetone. 

W. D. Williams, Brief history of the test tube clamp , Bull. Hist. Chem., 1991, 9, 37-39. 

Immerse the flask containing the volatile unknown liquid in the boiling water so that most of the flask is beneath the hot water as shown in Fig. 14.2. (You may need to weigh down the flask with a test tube clamp or a lead sinker.)... 

M Bunsen burner, high-temperature laboratory heat gun, or laboratory hot plate 0 2 13 x 100 or 15 x 120 mm test tubes H 2 small pieces of cardboard 13 2 small stirring rods H 2 small spatulas M test tube clamps B ring stand ffl 2 small vials B Sharpie... 

Fill tJie bath sonicator with room temperature water mixed with a couple of drops of liquid detergent. Using a ring stand and test tube clamp, suspend the MLV flask in the bath sonicator. The liquid level inside the flask should be equal to that of outside the flask. Sonicate for a time period of 20-40 min (see Note 4). 

Directions Mix thoroughly about 1 gram of arsenious oxide with three times its volume of powdered wood charcoal and place the mixture in the bottom of a test tube, clamped to the ring-stand in a horizontal position, and fitted with a one-hole stopper and delivery tube, which dips into lime water in a test tube. Heat the mixture until a dark deposit is observed near the mouth of the tube and then at once remove the delivery tube from the lime water. (1) Why (2) What is the deposit (3) Was any carbon dioxide formed (4) What is the evidence (5) Write an equation for the reaction upon heating. (6) What kind of reaction did the arsenious oxide undergo (7) What was the agent (8) What process is illustrated by the appearance of the deposit at a distance from the place at which it was formed ... 

When the water is hot but not boiling, place the test tube in the bath for 5 min. Use a test-tube clamp to remove the test tube from the bath and place in a test-tube holder until needed. 

Place one test tube in each water bath using a test-tube clamp. 

Weigh 0.25 g of powdered zinc, Zn, onto a piece of filter paper on a beam balance. Insert a rolled 4 x 6 piece of paper almost to the CuBr sample in the test tube used in part A, and add the powdered Zn to the test tube. Tap the test tube gently on the desktop so that all the Zn falls to the bottom of the test tube then remove the rolled paper. Swirl the test tube to mix the two powders, but not so vigorously as to get powder up the sides of the test tube. Clamp the test tube to a ring stand at the same angle and the same height as shown in FIGURE 40.1. 

With some volatile liquids, the previous method will not work. The compounds volatilize before they reach the sodium vapors. For such compounds, place 4 or 5 drops of the pure liquid in a clean, dry test tube, clamp it, and cautiously add the small piece of sodium metal. If there is any reaction, wait until it subsides. Then heat the test tube to red heat, and continue according to the instructions in the second paragraph of the preceding procedure. This stock solution or the one prepared by the general method above will be used in the nitrogen, sulfur, and halides tests that follow. 

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