BOTTOMS UP AND BUBBLES OUT

Benzyl cyanide (40 g. = 0 33 mole) is heated in a round-bottomed flask (capacity 0-5 1.), with a mixture of 50 c.c. of concentrated sulphuric acid and 30 c.c. of water. The flask is provided with an upright air condenser, and is placed in a conical (Babo) air bath. The heating is continued until the appearance of small bubbles of vapour indicates that a reaction, which rapidly becomes violent, has set in the liquid boils up, and white fumes are emitted. It is allowed to cool and then two volumes of water are added. After some time the phenylacetic acid which has crystallised out is filtered off with suction. If a sample of the material does not form a clear solution with sodium carbonate in water (presence of phenylacetamide), the whole of the crude material is shaken with sodium carbonate solution and the mixture is filtered. From the clear filtrate phenylacetic acid is reprecipitated with sulphuric acid, and can be recrystallised directly from a rather large volume of hot water or, after drying, from petrol ether. Because of its low melting point (76°) it often separates at first as an oil, but it can also be conveniently purified by distillation in vacuo from a sausage flask.2... 

To remove the naphtha layer (top layer) it was agreed that it would be best to siphon the bottom layer out of the jar and save it, instead, then clean out the jar containing the remaining nasty naphtha stuff. Using a plastic turkey baster we slowly squeezed the bulb as it passed through the layers into the jar. This forced small bubbles to pour from the nozzle, and prevented any naphtha from entering the baster before we could suck up the bottom layer. 

The rest of the chapter has been devoted to special topics and in materials science there are many possibilities. Those selected include the mechanism of the flotation of minerals in which the addition of a certain organic to the solution causes a specific mineral to become hydrophobic so that it is exposed to air bubbles, the bubbles stick to it and buoy the mineral up to the surface, leaving unwanted minerals on the bottom of the tank. It turns out that the mechanism of this phenomenon involves a mixed-potential concept in which the anodic oxidation of the organic collector, often a xanthate, allows it to form a hydrophobic film upon a semiconducting sulfide or oxide, but only if there is a partner reaction of oxygen reduction. This continues until there is almost full coverage with the dixanthate, and the surface is thereby made water-repelling. 

Calcite that precipitates directly at the water-air interface forms rafts of calcite crystals. The rafts float on the surface, supported by surface tension (Hill and Forti, 1997). When the water surface is disturbed by wind, seismicity, tidal fluctuations, flood inflow, or divers air bubbles, the rafts sink and often become cemented to the bottom (Fig. 8) (Riggs et al., 1994). Rafts start out as roughly circular aggregations of crystals that, if undisturbed, coalesce into large (up to 10 cm across) aggregations that are variable in general outline. Because the water surface in Browns Room is protected from disturbance by wind or flood inflow, rafts in Browns Room consistently are much larger than those that form in the open part of Devils... 

Diatoms living in the surf of the littoral zone are constantly on the move, migrating back and forth with the water. Offshore, they travel on air bubbles from the bottom of the shallow water to its surface. As a wave rolls to shore, diatoms ride it in and wash up on the beach. Here they secrete sticky mucus that helps them sink just below the sand s surface. As a wave rushes back to ocean, the diatoms wash out with it, back to their offshore position. From here, they float to the surface and reenter on another wave. 

To use this variation, the ethyl nitrite is first prepared as described above. The cold temperature is important to get best yields of the nitrite. Then the nitrite reaction mixture is poured into a suitable size round bottom flask, the glassware is set up as shown in Figure 8, and heat is applied to the nitrite mixture to bubble its vapors into the phenylacetone production reaction flask. Cold water should not be run through the condenser, as this may hold back the nitrite. Instead, the water should be room temperature. The nitrite solution will have to be heated to almost boiling to get the last of the nitrite to boil out of it. A yield of about 60 grams of ethyl nitrite can be expected from the directions given above. 

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