Fountain experiment

When the superfluid component flows through a capillary connecting two reservoirs, the concentration of the superfluid component in the source reservoir decreases, and that in the receiving reservoir increases. When both reservoirs are thermally isolated, the temperature of the source reservoir increases and that of the receiving reservoir decreases. This behavior is consistent with the postulated relationship between superfluid component concentration and temperature. The converse effect, which maybe thought of as the osmotic pressure of the superfluid component, also exists. If a reservoir of helium II held at constant temperature is coimected by a fine capillary to another reservoir held at a higher temperature, the helium II flows from the cooler reservoir to the warmer one. A popular demonstration of this effect is the fountain experiment (55). 

What was of higher interest in the Kampourakis and Tsaparlis study (2003) was the fact that the chosen practical activity was very involved. The fountain experiment is indeed a spectacular and impressive one, but this feature may be the cause of the failure of most students to pay attention to the stimuli relevant to the problem. Indeed, one could argue that the relevant to the problem stimuli were not the dominant stimuli of the experiment. In particular, the generation of ammonia in the flask was also producing working memory space overload (see below). 

For whoever drinks of this golden fountain, experiences a renovation of his whole nature, a vanishing of all unhealthy matter, a fresh supply of blood, a strengthening of the heart and of all the vitals, and a permanent bracing of every limb. For it opens all the pores, and through them bears away all that prevents the perfect health of the body, but allows all that is beneficial to remain therein unmolested. 

The ideal conditions for studying an atom is to have it at rest in free space, or in free fall as in a "fountain" experiment. Any process which confines an atom perturbs it However, as has been shown, at ultra low temperatures the perturbations of hydrogen due to a magnetic trap are small. Furthermore, the trap provides an enormous advantage in density compared to atomic beams or fountains density of 10u - 1012cm-3 is readily available. Thus, the trap is particularly attractive from the point of view of signal to noise ratio. 

Consequently, ammonia is very easily dissolved in water. An impressive way of showing this excellent solubility is with a so-called fountain experiment (Fig. 5). 

The reaction between HCl gas and water makes hydrogen chloride extremely soluble in water (see the fountain experiment, page 186). A considerable amount of heat is also given out, although this is quickly absorbed by the water. 

Very soluble gases (such as ammonia and hydrogen chloride) can be made to perform the fountain experiment . Figure 11.9 shows the experiment carried out with HCl(g). A flask is fitted with a cork and tube and filled with dry hydrogen chloride. Without delay, the flask is lowered into a deep bucket of water. So much gas dissolves in the water rising up the tube that a partial vacuum is created in the flask. This draws... 

We have already seen an impressive example for such an acid-base reaction, namely the ammonia fountain (Experiment 4.12). The formation of an alkaline (basic) milieu in the flask according to... 

Cs one. Gibble et have directly measured the s-wave scattering cross section and angular distribution in Cs atom collisions in an atomic fountain experiment at a temperature of T = 0.89/uK. 

It is very soluble in water. The fountain experiment shows this ... 

Hydrogen chloride is so soluble in water that you can do the fountain experiment with it (page 156). 

Figure 6.7 The famous fountain experiment illustrates both the very high solubility of hydrogen chloride in water, and the fact that the solution is acid, (a) An inverted flask full of HCl is connected by a tube to a reservoir containing water coloured by blue litmus. By blowing down the auxiliary tube, this water is forced up the connecting tube into the upper flask containing HCl. (b) Because HCl is so soluble, the first drops of water dissolve the contents of the flask, leaving a vacuum, (c) Water then fountains in without further assistance, filling the vacuum and the flask and turning red as it does so because of the acidity of the solution and the presence of litmus.

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