Boron clamp

Preparation of Amorphous Boron from Boric Acid Anhydride. (Each student performs only one of the experiments for preparing amorphous boron.) Put 2 g of boric acid anhydride into an iron crucible or onto an iron plate and roast it if the boric acid anhydride contains moisture, then when it is heated with magnesium an explosion may occur ). Triturate the boric acid anhydride as rapidly as possible (why ) in 4 mortar, weigh 1 g and mix it with 2 g of a magnesium powder. Place the mixture into a refractory test tube and fasten it in an inclined position in a clamp of a stand in a fume cupboard . First carefully heat the test tube with the mixture with the flame of a burner, and then strongly heat the bottom part of the tube. What do you observe ... 

Approximately 125 ml. of anhydrous ether is placed in a dry,f 250-ml. Erlenmeyer flask which is equipped with a 24/40 S.T. joint and a sidearm gas inlet (see Fig. 7). The stopcock on the sidearm is fitted with a retainer clip, the flask is stoppered, and the stopper is held in place with a spring clamp. The flask is weighed and is then attached to a lecture bottle of boron(III) chloride, % as shown in Fig. 7, by means of a 1-foot length of Tygon tubing which is punctured with a needle at least four times to allow release of excess pressure of boron(III) chloride. This apparatus is set up in the hood. The boron(III) chloride cylinder is opened cautiously, and BC18 is delivered into the flask for approximately 3 minutes while the flask is shaken vigorously to facilitate solution of the gas in the... 

A Pasteur pipet clamped in an O-ring thermometer adapter served as a convenient, adjustable gas-inlet tube. The large end of the pipet was fitted with a small rubber septum, through which a syringe needle was passed for introducing the boron trifluoride gas. 

With samples less than 5 mm in diameter, the flat sample holder depicted in Fig. 8.15B affords direct analyses provided the sample is nominally fiat. The holder is mounted to the end of the DIP and comprises a PTFE clamp assembly, support rods, boron nitride spacers and either stainless steel or aluminium anode orifice plates. The DIP is placed through the clamp assembly and the rf feedthrough is placed directly behind the sample (cathode), which locks it in place. The spacers separate the anode plate and the cathode in the same manner as the 0-ring seal in the rf-AES source design. The anode body in this case is the Ta ion volume enclosed by the anode plate and the ion exit orifice mounted to it the entire cell assembly is affixed to the commercial source cryo-cooling ring. 

Fig. 17. High-pressure clamp (15) main clamp screw (16) space for source and drive rod (17) source-centering device (18) upper centering plate (19) absorber (20) resistance thermometer (21) manometer leads (22) clamp mantle (23) lower centering plate (24) spring (25) central bore (26) boron carbide anvils (27) electric heater (28) thermometer leads. [Taken from Kalvius (1990).]...

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