Cartesian diver technique.

Micro respirometry studies, with the aid of the Cartesian diver (1, ,2), have presented several problems in manipulation. One of these has been the problem of mixing two or more solutions quantitatively in the diver, after the start of an experiment. Methods have been described accomplishing this (3,4). These methods could be mastered only by special training, patience, and skill. A much less difficult technique is now proposed in which a new type of diver vessel is employed, having an upper reaction chamber, a lower eh pansion chamber, and a relatively long neck. Precise control of overpressure necessary to mix the solutions in the diver is accomplished by the use of a sphygmomanometer bulb and valve, connected into the manifold system by a 3-way stop-cock (Fig. 1). The inner surfaces of the diver need to be coated with a hydrophobic surface such as Claritc, dissolved in toluene, only once. Thereafter there seems to be enough residual coating to take care of the requirements. Sudan III is mixed with the paraffin oil to facilitate visual observation of its position in the diver neck and phenolphthalein is used in the NaOH to detect any changes in pH.